JP7472951B2 - Resin composition layer - Google Patents

Description

The present invention relates to a resin composition layer. Furthermore, the present invention relates to a resin sheet including the resin composition layer; and a printed wiring board and a semiconductor device including an insulating layer formed of a cured product of the resin composition layer.

In recent years, in order to achieve the miniaturization of electronic devices, efforts are being made to further reduce the thickness of printed wiring boards. Accordingly, efforts are being made to miniaturize wiring circuits in inner layer substrates. For example, Patent Document 1 describes a resin sheet (adhesive film) that includes a support and a resin composition layer and is capable of supporting a low dielectric tangent.

JP 2014-5464 A

The present inventors have investigated how to make the resin composition layer of a resin sheet thinner in order to achieve further miniaturization and thinning of electronic devices. As a result of their investigation, the present inventors have found that when a thin resin composition layer is applied to an insulating layer, if a roughening treatment is performed after forming a via hole in the insulating layer, a haloing phenomenon occurs. Here, the haloing phenomenon refers to the occurrence of interlayer delamination between the insulating layer and the inner layer substrate around the via hole. This haloing phenomenon usually occurs when the resin around the via hole deteriorates during the formation of the via hole, and the deteriorated part is eroded during the roughening treatment. The deteriorated part is usually observed as a discolored part.

Furthermore, the inventors have found that when a thin resin composition layer is applied to the insulating layer, it becomes difficult to control the shape of the via hole, and it becomes difficult to obtain a via hole with a good shape. Here, a "good" shape of the via hole means that the taper ratio of the via hole is close to 1. Also, the taper ratio of the via hole means the ratio of the bottom diameter to the top diameter of the via hole.

All of the above-mentioned problems have arisen only by reducing the thickness of the resin composition layer, and are new problems that were not previously known. From the viewpoint of improving the reliability of electrical conduction between layers of printed wiring boards, it is desirable to solve these problems.

The present invention was devised in view of the above problems, and aims to provide a resin composition layer that can suppress the haloing phenomenon even when it is thin, and can provide an insulating layer that can form via holes of a good shape; a resin sheet that includes the resin composition layer; a printed wiring board that includes a thin insulating layer that can suppress the haloing phenomenon and can form via holes of a good shape; and a semiconductor device that includes the printed wiring board.

As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a resin composition containing in combination (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler having at least one of an average particle size of 100 ^nm or less and a specific surface area of 15 m2/g or more, and (D) a pigment, and have completed the present invention.
That is, the present invention includes the following.

[1] A resin composition layer having a thickness of 15 μm or less, comprising a resin composition,
A resin composition layer, the resin composition comprising: (A) an epoxy resin; (B) a curing agent; (C) an inorganic filler having an average particle size of 100 nm or less; and (D) a colorant.
[2] A resin composition layer having a thickness of 15 μm or less containing a resin composition,
A resin composition layer, the resin composition comprising: (A) an epoxy resin; (B) a curing agent; (C) an inorganic filler having a specific surface area of 15 m ² /g or more; and (D) a colorant.
[3] The resin composition layer according to [1] or [2], wherein the component (D) is a black or chromatic colorant.
[4] The resin composition layer according to any one of [1] to [3], wherein the component (D) is a black or blue colorant.
[5] The resin composition layer according to any one of [1] to [4], wherein the component (D) is a pigment.
[6] The resin composition layer according to any one of [1] to [5], wherein the amount of the component (D) is 0.1% by mass or more and 5% by mass or less, based on 100% by mass of non-volatile components in the resin composition.
[7] The resin composition layer according to any one of [1] to [6], wherein the amount of the component (C) is 60% by mass or less based on 100% by mass of non-volatile components in the resin composition.
[8] The resin composition layer according to any one of [1] to [7], comprising, as the component (A), at least one selected from the group consisting of bixylenol-type epoxy resins and fluorine-containing epoxy resins.
[9] The resin composition layer according to any one of [1] to [8], which is for forming an insulating layer for forming a conductor layer.
[10] The resin composition layer according to any one of [1] to [9], which is for forming an interlayer insulating layer of a printed wiring board.
[11] The resin composition layer according to any one of [1] to [10], which is for forming an insulating layer having a via hole with a top diameter of 35 μm or less.
[12] A support;
A resin sheet comprising: a resin composition layer according to any one of items [1] to [11] provided on a support.
[13] A printed wiring board comprising an insulating layer formed of a cured product of the resin composition layer according to any one of [1] to [11].
[14] A semiconductor device comprising the printed wiring board according to [13].

According to the present invention, it is possible to provide a resin composition layer that can suppress the haloing phenomenon even when it is thin, and can provide an insulating layer that can form via holes with a good shape; a resin sheet that includes the resin composition layer; a printed wiring board that includes a thin insulating layer that can suppress the haloing phenomenon and can form via holes with a good shape; and a semiconductor device that includes the printed wiring board.

FIG. 1 is a cross-sectional view showing a schematic diagram of an insulating layer obtained by curing a resin composition layer according to a first embodiment of the present invention, together with an inner layer substrate. FIG. 2 is a plan view that illustrates the surface of the insulating layer obtained by curing the resin composition layer according to the first embodiment of the present invention, opposite to the conductor layer. FIG. 3 is a cross-sectional view showing a roughening-treated insulating layer obtained by curing the resin composition layer according to the first embodiment of the present invention, together with an inner layer substrate. FIG. 4 is a schematic cross-sectional view of a printed wiring board according to a second embodiment of the present invention.

The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples given below, and may be modified as desired without departing from the scope of the claims of the present invention and their equivalents.

In the following description, the "resin component" of the resin composition refers to the non-volatile components contained in the resin composition excluding inorganic fillers and colorants.

[1. Overview of Resin Composition Layer]
The resin composition layer of the present invention is a thin resin composition layer having a thickness of a predetermined value or less. The resin composition contained in the resin composition layer of the present invention includes (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler having at least one of an average particle size of 100 nm or less and a specific surface area of 15 ^m2 /g or more, and (D) a colorant.
Therefore, the resin composition contained in the resin composition layer of the present invention can include both the first resin composition and the second resin composition described below.

A first resin composition comprising (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler having an average particle size of 100 nm or less, and (D) a colorant.

A second resin composition comprising (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler having a specific surface area of 15 m ² /g or more, and (D) a colorant.

Here, the (D) colorant refers to a pigment, a dye, or a combination thereof. In addition, pigments and dyes include components that may fall under the above-mentioned (A) to (C) components, but in the present invention, pigments and dyes are classified as (D) colorants. For example, carbon black with an average particle size of 100 nm or less is a pigment, and is therefore classified as a (D) colorant, not as a (C) component. In that sense, the resin composition contained in the resin composition layer of the present invention can be said to be a composition that contains a (D) colorant in combination with the above-mentioned (A) to (C) components other than the (D) colorant.

By using such a resin composition layer, a thin insulating layer can be obtained. Then, a via hole of a good shape can be formed in the obtained insulating layer, and further, the haloing phenomenon that occurs when a roughening treatment is applied to an insulating layer with a via hole formed therein can be suppressed, thereby achieving the desired effect of the present invention.

[2. Component (A): Epoxy resin]
Examples of the epoxy resin as component (A) include bixylenol type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol AF type epoxy resin, dicyclopentadiene type epoxy resin, trisphenol type epoxy resin, naphthol novolac type epoxy resin, phenol novolac type epoxy resin, tert-butyl-catechol type epoxy resin, naphthalene type epoxy resin, naphthol type epoxy resin, anthracene type epoxy resin, glycidylamine type epoxy resin, glycidyl ester type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, epoxy resin having a butadiene structure, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, cyclohexane type epoxy resin, cyclohexane dimethanol type epoxy resin, naphthylene ether type epoxy resin, trimethylol type epoxy resin, tetraphenylethane type epoxy resin, etc. The epoxy resin may be used alone or in combination of two or more types.

The resin composition preferably contains, as the epoxy resin (A), an epoxy resin having two or more epoxy groups in one molecule. From the viewpoint of significantly obtaining the desired effect of the present invention, the ratio of the epoxy resin having two or more epoxy groups in one molecule to 100% by mass of the non-volatile components of the epoxy resin (A) is preferably 50% by mass or more, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

Epoxy resins include epoxy resins that are liquid at a temperature of 20°C (hereinafter sometimes referred to as "liquid epoxy resins") and epoxy resins that are solid at a temperature of 20°C (hereinafter sometimes referred to as "solid epoxy resins"). The resin composition may contain only liquid epoxy resins or only solid epoxy resins as the epoxy resin (A), but it is preferable to contain a combination of liquid epoxy resins and solid epoxy resins. By using a combination of liquid epoxy resins and solid epoxy resins as the epoxy resin (A), it is possible to improve the flexibility of the resin composition layer and the breaking strength of the cured product of the resin composition layer.

As the liquid epoxy resin, a liquid epoxy resin having two or more epoxy groups in one molecule is preferable, and an aromatic liquid epoxy resin having two or more epoxy groups in one molecule is more preferable. Here, "aromatic" epoxy resin means an epoxy resin having an aromatic ring in its molecule.

Preferred liquid epoxy resins are bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, glycidyl amine type epoxy resins, and epoxy resins having a butadiene structure, with bisphenol A type epoxy resins, bisphenol F type epoxy resins, and cyclohexane type epoxy resins being more preferable.

Specific examples of liquid epoxy resins include DIC's "HP4032", "HP4032D", and "HP4032SS" (naphthalene type epoxy resins); Mitsubishi Chemical's "828US", "jER828EL", "825", and "Epicoat 828EL" (bisphenol A type epoxy resins); Mitsubishi Chemical's "jER807" and "1750" (bisphenol F type epoxy resins); Mitsubishi Chemical's "jER152" (phenol novolac type epoxy resin); and Mitsubishi Chemical's "630" and "630LSD" (glycidylamine type epoxy resins). Epoxy resins); "ZX1059" (a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin) manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd.; "EX-721" (glycidyl ester type epoxy resin) manufactured by Nagase ChemteX Corporation; "Celloxide 2021P" (alicyclic epoxy resin having an ester skeleton) manufactured by Daicel Corporation; "PB-3600" (epoxy resin having a butadiene structure) manufactured by Daicel Corporation; "ZX1658" and "ZX1658GS" (liquid 1,4-glycidylcyclohexane type epoxy resin) manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd. may be used alone or in combination of two or more types.

As the solid epoxy resin, a solid epoxy resin having three or more epoxy groups in one molecule is preferable, and an aromatic solid epoxy resin having three or more epoxy groups in one molecule is more preferable.

As solid epoxy resins, bixylenol type epoxy resins, naphthalene type epoxy resins, naphthalene type tetrafunctional epoxy resins, cresol novolac type epoxy resins, dicyclopentadiene type epoxy resins, trisphenol type epoxy resins, naphthol type epoxy resins, biphenyl type epoxy resins, naphthylene ether type epoxy resins, anthracene type epoxy resins, bisphenol A type epoxy resins, bisphenol AF type epoxy resins, and tetraphenylethane type epoxy resins are preferred, with bixylenol type epoxy resins, naphthalene type epoxy resins, bisphenol AF type epoxy resins, and naphthylene ether type epoxy resins being more preferred.

Specific examples of solid epoxy resins include DIC's "HP4032H" (naphthalene type epoxy resin); DIC's "HP-4700" and "HP-4710" (naphthalene type tetrafunctional epoxy resin); DIC's "N-690" (cresol novolac type epoxy resin); DIC's "N-695" (cresol novolac type epoxy resin); DIC's "HP-7200" (dicyclopentadiene type epoxy resin); DIC's "HP-7200HH", "HP-7200H", "EXA-7311", "EXA-7311-G3", "EXA-7311-G4", "EXA-7311-G4S", "HP6000" (naphthylene ether type epoxy resin); "EPPN-502H" (trisphenol type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC7000L" (naphthol novolac type epoxy resin) manufactured by Nippon Kayaku Co., Ltd.; "NC3000H", "NC30 00, "NC3000L", "NC3100" (biphenyl type epoxy resin); "ESN475V" (naphthalene type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; "ESN485" (naphthol novolac type epoxy resin) manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; "YX4000H", "YX4000", "YL6121" (biphenyl type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YX4000HK" (bixylenol type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd. "YX8800" (anthracene type epoxy resin) manufactured by Osaka Gas Chemicals Co., Ltd.; "PG-100" and "CG-500" manufactured by Osaka Gas Chemicals Co., Ltd.; "YL7760" (bisphenol AF type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "YL7800" (fluorene type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; "jER1010" (solid bisphenol A type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd.; and "jER1031S" (tetraphenylethane type epoxy resin) manufactured by Mitsubishi Chemical Co., Ltd. These may be used alone or in combination of two or more types.

When a liquid epoxy resin and a solid epoxy resin are used in combination as the (A) epoxy resin, the ratio of the amounts thereof (liquid epoxy resin:solid epoxy resin) is preferably 1:1 to 1:20, more preferably 1:2 to 1:15, and particularly preferably 1:5 to 1:13, by mass. When the ratio of the liquid epoxy resin to the solid epoxy resin is within this range, the desired effects of the present invention can be significantly obtained. Furthermore, when used in the form of a resin sheet, appropriate adhesion is usually achieved. Furthermore, when used in the form of a resin sheet, sufficient flexibility is usually obtained, improving handling. Furthermore, a cured product having sufficient breaking strength can usually be obtained.

Furthermore, the resin composition preferably contains at least one type of epoxy resin (A) selected from the group consisting of bixylenol-type epoxy resins and fluorine-containing epoxy resins. Some (D) colorants, such as pigments, have the effect of increasing the viscosity of the resin composition, but by using a bixylenol-type epoxy resin, the increase in viscosity caused by the use of the (D) colorant can be suppressed. In addition, fluorine-containing epoxy resins such as bisphenol AF-type epoxy resins can increase the dispersibility of the (D) colorant in the resin composition.

The epoxy equivalent of the (A) epoxy resin is preferably 50 to 5,000, more preferably 50 to 3,000, even more preferably 80 to 2,000, and even more preferably 110 to 1,000. This range ensures sufficient crosslink density in the cured product of the resin composition layer, resulting in an insulating layer with low surface roughness. The epoxy equivalent is the mass of a resin containing one equivalent of epoxy groups. This epoxy equivalent can be measured in accordance with JIS K7236.

The weight average molecular weight (Mw) of the epoxy resin (A) is preferably 100 to 5,000, more preferably 250 to 3,000, and even more preferably 400 to 1,500, from the viewpoint of significantly obtaining the desired effects of the present invention.
The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC) as a polystyrene equivalent value.

The amount of epoxy resin (A) in the resin composition is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, based on 100% by mass of the resin components in the resin composition, from the viewpoint of obtaining an insulating layer that exhibits good mechanical strength and insulating reliability. The upper limit of the epoxy resin content is preferably 90% by mass or less, more preferably 85% by mass or less, and particularly preferably 83% by mass or less, from the viewpoint of significantly obtaining the desired effects of the present invention.

[3. Component (B): Curing Agent]
The resin composition contains a curing agent as component (B). The curing agent (B) usually has the function of reacting with the epoxy resin (A) to cure the resin composition.

As the (B) curing agent, a material having the effect of curing the (A) epoxy resin can be used. Examples of the (B) curing agent include active ester curing agents, phenolic curing agents, naphthol curing agents, benzoxazine curing agents, cyanate ester curing agents, and carbodiimide curing agents. In addition, the curing agent may be used alone or in combination of two or more types.

As the active ester curing agent, a compound having one or more active ester groups in one molecule can be used. Among them, as the active ester curing agent, a compound having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds, is preferable. The active ester curing agent is preferably one obtained by a condensation reaction between a carboxylic acid compound and/or a thiocarboxylic acid compound and a hydroxy compound and/or a thiol compound. In particular, from the viewpoint of improving heat resistance, an active ester curing agent obtained from a carboxylic acid compound and a hydroxy compound is preferable, and an active ester curing agent obtained from a carboxylic acid compound and a phenol compound and/or a naphthol compound is more preferable.

Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

Examples of phenol compounds or naphthol compounds include hydroquinone, resorcin, bisphenol A, bisphenol F, bisphenol S, phenolphthaline, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, and phenol novolak. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

Specific examples of preferred active ester-based curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated product of phenol novolac, and active ester compounds containing a benzoylated product of phenol novolac. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The term "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

Commercially available active ester curing agents include active ester compounds containing a dicyclopentadiene-type diphenol structure, such as "EXB9451", "EXB9460", "EXB9460S", "HPC-8000-65T", "HPC-8000H-65TM", "EXB-8000L-65TM", and "EXB-8150-65T" (manufactured by DIC Corporation); active ester compounds containing a naphthalene structure, such as "EXB9416-70BK" (manufactured by DIC Corporation); and active ester compounds containing an acetylated product of phenol novolac, such as "EXB9420-1000BK" (manufactured by DIC Corporation). Examples of ester compounds include "DC808" (manufactured by Mitsubishi Chemical Corporation); "YLH1026" (manufactured by Mitsubishi Chemical Corporation) is an active ester compound containing a benzoyl derivative of phenol novolac; "DC808" (manufactured by Mitsubishi Chemical Corporation) is an active ester-based hardener that is an acetylated derivative of phenol novolac; "YLH1026" (manufactured by Mitsubishi Chemical Corporation), "YLH1030" (manufactured by Mitsubishi Chemical Corporation), and "YLH1048" (manufactured by Mitsubishi Chemical Corporation) are active ester-based hardeners that are benzoyl derivatives of phenol novolac.

From the viewpoint of heat resistance and water resistance, phenol-based and naphthol-based curing agents having a novolac structure are preferred. From the viewpoint of adhesion to the conductor layer, nitrogen-containing phenol-based curing agents are preferred, and triazine skeleton-containing phenol-based curing agents are more preferred.

Specific examples of phenol-based and naphthol-based curing agents include "MEH-7700", "MEH-7810", and "MEH-7851" manufactured by Meiwa Kasei Co., Ltd.; "NHN", "CBN", and "GPH" manufactured by Nippon Kayaku Co., Ltd.; "SN170", "SN180", "SN190", "SN475", "SN485", "SN495", "SN-495V", and "SN375" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.; and "TD-2090", "LA-7052", "LA-7054", "LA-1356", "LA-3018-50P", and "EXB-9500" manufactured by DIC Corporation.

Specific examples of benzoxazine-based curing agents include "HFB2006M" manufactured by Showa Polymer Co., Ltd., and "P-d" and "F-a" manufactured by Shikoku Chemical Industry Co., Ltd.

Examples of cyanate ester curing agents include bifunctional cyanate resins such as bisphenol A dicyanate, polyphenol cyanate, oligo(3-methylene-1,5-phenylene cyanate), 4,4'-methylenebis(2,6-dimethylphenyl cyanate), 4,4'-ethylidene diphenyl dicyanate, hexafluorobisphenol A dicyanate, 2,2-bis(4-cyanate)phenylpropane, 1,1-bis(4-cyanate phenylmethane), bis(4-cyanate-3,5-dimethylphenyl)methane, 1,3-bis(4-cyanate phenyl-1-(methylethylidene))benzene, bis(4-cyanate phenyl)thioether, and bis(4-cyanate phenyl)ether; polyfunctional cyanate resins derived from phenol novolac and cresol novolac; and prepolymers in which these cyanate resins have been partially converted to triazine. Specific examples of cyanate ester-based hardeners include Lonza Japan's "PT30" and "PT60" (phenol novolac-type multifunctional cyanate ester resins), "ULL-950S" (multifunctional cyanate ester resin), "BA230" and "BA230S75" (prepolymers in which part or all of bisphenol A dicyanate has been triazine-converted into a trimer).

Specific examples of carbodiimide-based curing agents include "V-03" and "V-07" manufactured by Nisshinbo Chemical Co., Ltd.

Among the above, from the viewpoint of significantly obtaining the desired effect of the present invention, an active ester-based curing agent is preferred as the (B) curing agent. When an active ester-based curing agent is used, the content of the active ester-based curing agent relative to 100% by mass of the (B) curing agent is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and is preferably 75% by mass or less, more preferably 73% by mass or less, even more preferably 70% by mass or less, from the viewpoint of significantly obtaining the desired effect of the present invention.

The amount of (B) curing agent in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the resin components in the resin composition, from the viewpoint of significantly obtaining the desired effect of the present invention, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less.

When the number of epoxy groups in the (A) epoxy resin is taken as 1, the number of active groups in the (B) curing agent is preferably 0.1 or more, more preferably 0.2 or more, even more preferably 0.24 or more, and preferably 2 or less, more preferably 1.5 or less, even more preferably 1 or less, and particularly preferably 0.5 or less. Here, the "number of epoxy groups in the (A) epoxy resin" refers to the total value obtained by dividing the mass of the non-volatile components of the (A) epoxy resin present in the resin composition by the epoxy equivalent. Also, the "number of active groups in the (B) curing agent" refers to the total value obtained by dividing the mass of the non-volatile components of the (B) curing agent present in the resin composition by the active group equivalent. When the number of epoxy groups in the (A) epoxy resin is taken as 1, the desired effect of the present invention can be significantly obtained by the number of active groups in the (B) curing agent being within the above range, and moreover, the heat resistance of the cured product of the resin composition layer is usually further improved.

[4. Component (C): Inorganic filler having at least one of an average particle size of 100 nm or less and a specific surface area of 15 m ² /g or more]
The resin composition contains an inorganic filler as component (C). The inorganic filler can reduce the thermal expansion coefficient of the cured resin composition layer, so that an insulating layer with suppressed reflow warpage can be obtained. In addition, the inorganic filler as component (C) has at least one of an average particle size of 100 nm or less and a specific surface area of 15 m ² /g or more. By using component (C) having at least one of an average particle size and a specific surface area in such range as an inorganic filler in combination with (A) an epoxy resin, (B) a curing agent, and (D) a colorant, an insulating layer capable of forming a via hole with a good shape can be realized.

As the material of the inorganic filler, an inorganic compound is used. Examples of the material of the inorganic filler include silica, alumina, glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, magnesium oxide, boron nitride, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, titanium oxide, zirconium oxide, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, and zirconium tungstate phosphate. Among these, silica is particularly suitable. Examples of silica include amorphous silica, fused silica, crystalline silica, synthetic silica, and hollow silica. In addition, spherical silica is preferable as the silica. The inorganic filler may be used alone or in combination of two or more types.

The average particle size of component (C) is usually 100 nm or less, preferably 90 nm or less, and more preferably 80 nm or less, from the viewpoint of making the insulating layer thin and enabling control of the shape of the via hole to achieve a good shape. The lower limit of the average particle size is not particularly limited, but is preferably 50 nm or more, 60 nm or more, or 70 nm or more. Examples of commercially available inorganic fillers having such an average particle size include "UFP-30" and "UFP-40" manufactured by Denki Kagaku Kogyo Co., Ltd.

The average particle size of the inorganic filler can be measured by a laser diffraction/scattering method based on the Mie scattering theory. Specifically, a particle size distribution of the inorganic filler is created on a volume basis using a laser diffraction/scattering particle size distribution measuring device, and the median diameter is taken as the average particle size. A preferable measurement sample is an inorganic filler dispersed in methyl ethyl ketone using ultrasonic waves. Examples of laser diffraction/scattering particle size distribution measuring devices that can be used include the LA-500 manufactured by Horiba, Ltd. and the SALD-2200 manufactured by Shimadzu Corporation.

The specific surface area of component (C) is usually 15 m ² /g or more, preferably 20 m ² /g or more, and particularly preferably 30 m ² /g or more, from the viewpoint of easily controlling the shape of the via hole and realizing a good shape. In addition, component (C) having such a large specific surface area generally has a small particle size, so that the insulating layer can be made thin. There is no particular upper limit, but it is preferably 60 m ² /g or less, 50 m ² /g or less, or 40 m ² /g or less. The specific surface area of the inorganic filler can be measured by the BET method.

The inorganic filler as component (C) is preferably treated with a surface treatment agent from the viewpoint of improving moisture resistance and dispersibility. Examples of surface treatment agents include fluorine-containing silane coupling agents, aminosilane coupling agents, epoxysilane coupling agents, mercaptosilane coupling agents, silane coupling agents, alkoxysilanes, organosilazane compounds, titanate coupling agents, etc. Furthermore, the surface treatment agents may be used alone or in any combination of two or more types.

Examples of commercially available surface treatment agents include Shin-Etsu Chemical's "KBM403" (3-glycidoxypropyltrimethoxysilane), Shin-Etsu Chemical's "KBM803" (3-mercaptopropyltrimethoxysilane), Shin-Etsu Chemical's "KBE903" (3-aminopropyltriethoxysilane), Shin-Etsu Chemical's "KBM573" (N-phenyl-3-aminopropyltrimethoxysilane), Shin-Etsu Chemical's "SZ-31" (hexamethyldisilazane), Shin-Etsu Chemical's "KBM103" (phenyltrimethoxysilane), Shin-Etsu Chemical's "KBM-4803" (long-chain epoxy-type silane coupling agent), and Shin-Etsu Chemical's "KBM-7103" (3,3,3-trifluoropropyltrimethoxysilane).

From the viewpoint of improving the dispersibility of the inorganic filler, it is preferable that the degree of surface treatment with the surface treatment agent falls within a specified range. Specifically, 100 parts by mass of the inorganic filler is preferably surface-treated with 0.2 parts by mass to 5 parts by mass of the surface treatment agent, more preferably with 0.2 parts by mass to 3 parts by mass, and more preferably with 0.3 parts by mass to 2 parts by mass.

The degree of surface treatment by the surface treatment agent can be evaluated by the amount of carbon per unit surface area of the inorganic filler. From the viewpoint of improving the dispersibility of the inorganic filler, the amount of carbon per unit surface area of the inorganic filler is preferably 0.02 mg/m ² or more, more preferably 0.1 mg/m ² or more, and even more preferably 0.2 mg/m ² or more. On the other hand, from the viewpoint of suppressing the increase in the melt viscosity of the resin varnish and the melt viscosity in the sheet form, it is preferably 1 mg/m ² or less, more preferably 0.8 mg/m ² or less, and even more preferably 0.5 mg/m ² or less.

The amount of carbon per unit surface area of the inorganic filler can be measured after the surface-treated inorganic filler is washed with a solvent (e.g., methyl ethyl ketone (MEK)). Specifically, a sufficient amount of MEK as a solvent is added to the inorganic filler that has been surface-treated with a surface treatment agent, and ultrasonic cleaning is performed at 25°C for 5 minutes. After removing the supernatant and drying the solids, the amount of carbon per unit surface area of the inorganic filler can be measured using a carbon analyzer. An example of a carbon analyzer that can be used is the "EMIA-320V" manufactured by Horiba, Ltd.

The amount of the (C) component in the resin composition is preferably 30% by mass or more, more preferably 35% by mass or more, and even more preferably 40% by mass or more, based on 100% by mass of the nonvolatile components in the resin composition, from the viewpoint of lowering the dielectric tangent of the insulating layer. In addition, in the past, when the layer of the resin composition containing such a large amount of inorganic filler is thin, it was difficult to improve the shape of the via hole, and in particular, when the amount of inorganic filler relative to 100% by mass of the nonvolatile components in the resin composition is 50% by mass or more, it was particularly difficult to form a via hole with a good shape. Therefore, from the viewpoint of effectively utilizing the advantage of the present invention that it is possible to form a via hole with a good shape, which was particularly difficult in the past, the amount of the (C) component relative to 100% by mass of the nonvolatile components in the resin composition is preferably 50% by mass or more, and particularly preferably 55% by mass or more. In addition, the upper limit of the amount of the (C) component relative to 100% by mass of the nonvolatile components in the resin composition is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less, or 75% by mass or less, from the viewpoint of increasing the mechanical strength of the insulating layer. Furthermore, since this allows the shape of the via holes to be particularly good, it is particularly preferable that the amount of component (C) is 60% by mass or less relative to 100% by mass of the non-volatile components in the resin composition.

[5. Component (D): Colorant]
The resin composition contains a colorant as component (D). Since the resin composition contains the colorant (D), the resin composition layer usually has the color of the colorant (D).

As the (D) colorant, an achromatic colorant or a chromatic colorant may be used. Of these, from the viewpoint of obtaining the desired effect of the present invention significantly, a non-white colorant is preferable as the (D) colorant. Of these, from the viewpoint of particularly effectively suppressing the haloing phenomenon, a black or chromatic colorant is preferable as the (D) colorant, a black, blue or green colorant is more preferable, and a black or blue colorant is even more preferable.

As the colorant (D), a pigment may be used, a dye may be used, or a combination of a pigment and a dye may be used. Among these, as the colorant (D), a pigment is preferable. Since pigments have high coloring ability, they can effectively color the resin composition layer. Therefore, pigments can increase the light absorption ability of the resin composition layer, and therefore the haloing phenomenon can be particularly effectively suppressed.

Examples of pigments include blue pigments such as phthalocyanine pigments, anthraquinone pigments, and dioxazine pigments. Examples of yellow pigments include monoazo pigments, disazo pigments, condensed azo pigments, benzimidazolone pigments, isoindolinone pigments, and anthraquinone pigments. Examples of red pigments include monoazo pigments, disazo pigments, azo lake pigments, benzimidazolone pigments, perylene pigments, diketopyrrolopyrrole pigments, condensed azo pigments, anthraquinone pigments, and quinacridone pigments. Examples of black pigments include carbon black and graphite. Examples of green pigments include phthalocyanine pigments.

The pigment is usually not dissolved in the epoxy resin (A) in the resin composition and exists as particles. The average particle size of the pigment particles is preferably within the same range as the range described as the average particle size range of component (C). The specific surface area of the pigment particles is also preferably within the same range as the range described as the specific surface area range of component (C). This allows the insulating layer to be made thin, and also makes it possible to control the shape of the via hole and achieve a good shape. The average particle size and specific surface area of the pigment can be measured in the same manner as for component (C).

(D) The coloring agent may be used alone or in any combination of two or more types in any ratio.

The amount of colorant (D) in the resin composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and particularly preferably 1.0% by mass or more, based on 100% by mass of the non-volatile components in the resin composition, and is preferably 5% by mass or less, more preferably 4% by mass or less, and particularly preferably 3% by mass or less. By having the amount of colorant (D) in the above range, the haloing phenomenon can be effectively suppressed.

[6. (E) Component: Thermoplastic resin]
In addition to the above-mentioned components, the resin composition may further contain (E) a thermoplastic resin as an optional component.

Examples of thermoplastic resins as component (E) include phenoxy resins, polyvinyl acetal resins, polyolefin resins, polybutadiene resins, polyimide resins, polyamideimide resins, polyetherimide resins, polysulfone resins, polyethersulfone resins, polyphenylene ether resins, polycarbonate resins, polyetheretherketone resins, and polyester resins. Among these, phenoxy resins are preferred from the viewpoint of obtaining the desired effects of the present invention significantly and from the viewpoint of obtaining an insulating layer that has small surface roughness and is particularly excellent in adhesion to the conductor layer. In addition, the thermoplastic resins may be used alone or in combination of two or more types.

Examples of phenoxy resins include phenoxy resins having one or more skeletons selected from the group consisting of bisphenol A skeleton, bisphenol F skeleton, bisphenol S skeleton, bisphenolacetophenone skeleton, novolac skeleton, biphenyl skeleton, fluorene skeleton, dicyclopentadiene skeleton, norbornene skeleton, naphthalene skeleton, anthracene skeleton, adamantane skeleton, terpene skeleton, and trimethylcyclohexane skeleton. The terminal of the phenoxy resin may be any functional group such as a phenolic hydroxyl group or an epoxy group.

Specific examples of phenoxy resins include Mitsubishi Chemical's "1256" and "4250" (both phenoxy resins containing a bisphenol A skeleton); Mitsubishi Chemical's "YX8100" (phenoxy resin containing a bisphenol S skeleton); Mitsubishi Chemical's "YX6954" (phenoxy resin containing a bisphenol acetophenone skeleton); Nippon Steel & Sumikin Chemical's "FX280" and "FX293"; Mitsubishi Chemical's "YL7500BH30", "YX6954BH30", "YX7553", "YX7553BH30", "YL7769BH30", "YL6794", "YL7213", "YL7290" and "YL7482".

Examples of polyvinyl acetal resins include polyvinyl formal resins and polyvinyl butyral resins, with polyvinyl butyral resins being preferred. Specific examples of polyvinyl acetal resins include Denka Butyral 4000-2, Denka Butyral 5000-A, Denka Butyral 6000-C, and Denka Butyral 6000-EP manufactured by Denki Kagaku Kogyo Co., Ltd.; and S-LEC BH series, BX series (e.g. BX-5Z), KS series (e.g. KS-1), BL series, and BM series manufactured by Sekisui Chemical Co., Ltd.

Specific examples of polyimide resins include "Rikacoat SN20" and "Rikacoat PN20" manufactured by New Japan Chemical Co., Ltd. Specific examples of polyimide resins also include modified polyimides such as linear polyimides obtained by reacting bifunctional hydroxyl-terminated polybutadiene, a diisocyanate compound, and a tetrabasic acid anhydride (polyimides described in JP-A-2006-37083), and polysiloxane skeleton-containing polyimides (polyimides described in JP-A-2002-12667 and JP-A-2000-319386, etc.).

Specific examples of polyamide-imide resins include "Viromax HR11NN" and "Viromax HR16NN" manufactured by Toyobo Co., Ltd. Specific examples of polyamide-imide resins include modified polyamide-imides such as "KS9100" and "KS9300" (polyamide-imide containing a polysiloxane skeleton) manufactured by Hitachi Chemical Co., Ltd.

An example of a polyethersulfone resin is "PES5003P" manufactured by Sumitomo Chemical Co., Ltd.

Specific examples of polyphenylene ether resins include the oligophenylene ether styrene resin "OPE-2St 1200" manufactured by Mitsubishi Gas Chemical Co., Inc.

Specific examples of polysulfone resins include polysulfones "P1700" and "P3500" manufactured by Solvay Advanced Polymers.

The weight average molecular weight (Mw) of the (E) thermoplastic resin is preferably 8,000 or more, more preferably 10,000 or more, and particularly preferably 20,000 or more, from the viewpoint of significantly obtaining the desired effects of the present invention, and is preferably 70,000 or less, more preferably 60,000 or less, and particularly preferably 50,000 or less.

When a thermoplastic resin (E) is used, the amount of the thermoplastic resin (E) in the resin composition is, from the viewpoint of significantly obtaining the desired effect of the present invention, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1% by mass or more, relative to 100% by mass of the resin components in the resin composition, and is preferably 15% by mass or less, more preferably 12% by mass or less, and even more preferably 10% by mass or less.

[7. Component (F): Curing Accelerator]
In addition to the above-mentioned components, the resin composition may further contain (F) a curing accelerator as an optional component.

Examples of the curing accelerator include phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, guanidine-based curing accelerators, and metal-based curing accelerators. Among them, phosphorus-based curing accelerators, amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are preferred, and amine-based curing accelerators, imidazole-based curing accelerators, and metal-based curing accelerators are more preferred. The curing accelerators may be used alone or in combination of two or more types.

Examples of phosphorus-based curing accelerators include triphenylphosphine, phosphonium borate compounds, tetraphenylphosphonium tetraphenylborate, n-butylphosphonium tetraphenylborate, tetrabutylphosphonium decanoate, (4-methylphenyl)triphenylphosphonium thiocyanate, tetraphenylphosphonium thiocyanate, butyltriphenylphosphonium thiocyanate, etc., with triphenylphosphine and tetrabutylphosphonium decanoate being preferred.

Examples of amine-based curing accelerators include trialkylamines such as triethylamine and tributylamine, 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred.

Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 1,2-dimethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-undecylimidazolium trimellitate, 1-cyanoethyl-2-phenylimidazolium trimellitate, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4 -diamino-6-[2'-undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl Examples of the imidazole compounds include 1-ethyl-4-methyl-5-hydroxymethylimidazole, 2,3-dihydro-1H-pyrrolo[1,2-a]benzimidazole, 1-dodecyl-2-methyl-3-benzylimidazolium chloride, 2-methylimidazoline, 2-phenylimidazoline, and adducts of imidazole compounds and epoxy resins, with 2-ethyl-4-methylimidazole and 1-benzyl-2-phenylimidazole being preferred.

Commercially available imidazole curing accelerators may be used, such as "P200-H50" manufactured by Mitsubishi Chemical Corporation.

Examples of guanidine-based curing accelerators include dicyandiamide, 1-methylguanidine, 1-ethylguanidine, 1-cyclohexylguanidine, 1-phenylguanidine, 1-(o-tolyl)guanidine, dimethylguanidine, diphenylguanidine, trimethylguanidine, tetramethylguanidine, pentamethylguanidine, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene, Examples include o[4.4.0]dec-5-ene, 1-methylbiguanide, 1-ethylbiguanide, 1-n-butylbiguanide, 1-n-octadecylbiguanide, 1,1-dimethylbiguanide, 1,1-diethylbiguanide, 1-cyclohexylbiguanide, 1-allylbiguanide, 1-phenylbiguanide, and 1-(o-tolyl)biguanide, and dicyandiamide and 1,5,7-triazabicyclo[4.4.0]dec-5-ene are preferred.

Metal-based curing accelerators include, for example, organometallic complexes or organometallic salts of metals such as cobalt, copper, zinc, iron, nickel, manganese, and tin. Specific examples of organometallic complexes include organocobalt complexes such as cobalt (II) acetylacetonate and cobalt (III) acetylacetonate, organocopper complexes such as copper (II) acetylacetonate, organozinc complexes such as zinc (II) acetylacetonate, organoiron complexes such as iron (III) acetylacetonate, organonickel complexes such as nickel (II) acetylacetonate, and organomanganese complexes such as manganese (II) acetylacetonate. Organometallic salts include, for example, zinc octylate, tin octylate, zinc naphthenate, cobalt naphthenate, tin stearate, and zinc stearate.

When a curing accelerator (F) is used, the amount of the curing accelerator (F) in the resin composition is, from the viewpoint of significantly obtaining the desired effect of the present invention, preferably 0.01% by mass or more, more preferably 0.05% by mass or more, even more preferably 0.1% by mass or more, relative to 100% by mass of the resin components of the resin composition, and is preferably 3% by mass or less, more preferably 2% by mass or less, even more preferably 1.5% by mass or less.

[8. (G) Component: Optional Additive]
The resin composition may further contain any additives as optional components other than the above-mentioned components. Examples of such additives include organic fillers; resin additives such as flame retardants, thickeners, defoamers, leveling agents, and adhesion promoters; and the like. These additives may be used alone or in combination of two or more.

[9. Thickness of Resin Composition Layer]
The resin composition layer is a layer formed of the above-mentioned resin composition and has a thickness of a predetermined value or less. The specific thickness of the resin composition layer is usually 15 μm or less, preferably 14 μm or less, and more preferably 12 μm or less. Conventionally, the thickness of the resin composition layer for forming the insulating layer of a printed wiring board was generally thicker than this. In contrast, when the present inventor thinned a resin composition layer of a general composition as described above, it was found that such a thin resin composition layer caused problems that were not previously known, such as difficulty in controlling the shape of the via hole and the occurrence of the haloing phenomenon after roughening treatment. From the viewpoint of solving such new problems and contributing to the thinning of the printed wiring board, the resin composition layer of the present invention is provided thinly as described above. The lower limit of the thickness of the resin composition layer is arbitrary, and can be, for example, 1 μm or more, 3 μm or more.

[10. Characteristics of Resin Composition Layer]
By curing the resin composition layer of the present invention, a thin insulating layer formed of the cured product of the resin composition layer can be obtained. A via hole with a good shape can be formed in this insulating layer. In addition, when a via hole is formed in this insulating layer and a roughening treatment is performed, the haloing phenomenon can be suppressed. Hereinafter, these effects will be described with reference to the drawings.

1 is a cross-sectional view showing an insulating layer 100 obtained by curing a resin composition layer according to a first embodiment of the present invention, together with an inner layer substrate 200. In this Fig. 1, a cross section of the insulating layer 100 is shown cut along a plane passing through a center 120C of a bottom 120 of a via hole 110 and parallel to the thickness direction of the insulating layer 100.
As shown in FIG. 1, the insulating layer 100 according to the first embodiment of the present invention is a layer obtained by curing a resin composition layer formed on an inner layer substrate 200 including a conductor layer 210, and is made of the cured product of the resin composition layer. In addition, a via hole 110 is formed in the insulating layer 100. The via hole 110 is generally formed in a forward tapered shape in which the diameter is larger closer to the surface 100U of the insulating layer 100 opposite the conductor layer 210 and the diameter is smaller closer to the conductor layer 210, and is ideally formed in a columnar shape having a constant diameter in the thickness direction of the insulating layer 100. The via hole 110 is usually formed by irradiating the surface 100U of the insulating layer 100 opposite the conductor layer 210 with laser light to remove a part of the insulating layer 100.

The bottom of the via hole 110 on the conductor layer 210 side is appropriately called the "via bottom" and indicated by the reference symbol 120. The diameter of this via bottom 120 is called the bottom diameter Lb. The opening formed on the opposite side of the via hole 110 from the conductor layer 210 is appropriately called the "via top" and indicated by the reference symbol 130. The diameter of this via top 130 is called the top diameter Lt. Usually, the via bottom 120 and the via top 130 are formed so that their planar shape is circular when viewed from the thickness direction of the insulating layer 100, but they may be elliptical. When the planar shape of the via bottom 120 and the via top 130 is elliptical, the bottom diameter Lb and the top diameter Lt respectively represent the major diameter of the elliptical shape.

In this case, the closer the taper ratio Lb/Lt (%) obtained by dividing the bottom diameter Lb by the top diameter Lt is to 100%, the better the shape of the via hole 110 is. By using the resin composition layer of the present invention, it is possible to easily control the shape of the via hole 110, and therefore it is possible to realize a via hole 110 with a taper ratio Lb/Lt close to 100%.

For example, when an insulating layer 100 obtained by heating a resin composition layer at 100° C. for 30 minutes and then heating and curing at 180° C. for 30 minutes is irradiated with _CO2 laser light under the conditions of a mask diameter of 1 mm, a pulse width of 16 μs, energy of 0.2 mJ/shot, number of shots of 2, and burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm±2 μm, the taper ratio Lb/Lt of the via hole 110 can be preferably set to 75% to 100%, more preferably 80% to 100%, and particularly preferably 85% to 100%.

The taper ratio Lb/Lt of the via hole 110 can be calculated from the bottom diameter Lb and top diameter Lt of the via hole 110. The bottom diameter Lb and top diameter Lt of the via hole 110 can be measured by using a focused ion beam (FIB) to cut out the insulating layer 100 so that a cross section parallel to the thickness direction of the insulating layer 100 and passing through the center 120C of the via bottom 120 is revealed, and then observing the cross section with an electron microscope.

FIG. 2 is a plan view showing a schematic view of a surface 100U of an insulating layer 100 obtained by curing a resin composition layer according to the first embodiment of the present invention, the surface 100U being opposite to a conductor layer 210 (not shown in FIG. 2).
2, when looking at the insulating layer 100 with a via hole 110 formed therein, a discolored area 140 where the insulating layer 100 has changed color may be observed around the via hole 110. The discolored area 140 may be formed due to deterioration of the resin when the via hole 110 is formed, and is usually formed continuously from the via hole 110. In many cases, the discolored area 140 is a whitened area.

3 is a cross-sectional view showing a roughening-treated insulating layer 100 obtained by curing the resin composition layer according to the first embodiment of the present invention, together with an inner layer substrate 200. In FIG. 3, a cross section of the insulating layer 100 is shown cut along a plane passing through the center 120C of the via bottom 120 of the via hole 110 and parallel to the thickness direction of the insulating layer 100.
3, when a roughening treatment is performed on the insulating layer 100 in which the via hole 110 is formed, a haloing phenomenon occurs, and the insulating layer 100 in the discolored portion 140 peels off from the conductor layer 210, and a gap portion 160 is formed that continues from the edge 150 of the via bottom 120. This gap portion 160 is usually formed by erosion of the discolored portion 140 during the roughening treatment.

By using the resin composition layer of the present invention, the above-mentioned haloing phenomenon can be suppressed. Therefore, peeling of the insulating layer 100 from the conductor layer 210 can be suppressed, and the size of the gap portion 160 can be reduced.

The edge 150 of the via bottom 120 corresponds to the edge on the inner circumference side of the gap 160. Therefore, the distance Wb from the edge 150 of the via bottom 120 to the outer circumference side end 170 of the gap 160 (i.e., the end farther from the center 120C of the via bottom 120) corresponds to the size of the gap 160 in the in-plane direction. Here, the in-plane direction refers to the direction perpendicular to the thickness direction of the insulating layer 100. In the following description, the distance Wb may be referred to as the halo distance Wb from the edge 150 of the via bottom 120 of the via hole 110. The degree of suppression of the halo phenomenon can be evaluated by the halo distance Wb from the edge 150 of the via bottom 120. Specifically, it can be evaluated that the halo distance Wb from the edge 150 of the via bottom 120 is smaller, the more effectively the halo phenomenon can be suppressed.

For example, the resin composition layer is heated at 100 ° C for 30 minutes, then heated at 180 ° C for 30 minutes to harden the insulating layer 100, and the insulating layer 100 is irradiated with _CO2 laser light under the conditions of a mask diameter of 1 mm, a pulse width of 16 μs, energy of 0.2 mJ / shot, shot number 2, and burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm ± 2 μm. Then, the insulating layer 100 is immersed in a swelling liquid at 60 ° C for 10 minutes, then immersed in an oxidizing agent solution at 80 ° C for 20 minutes, then immersed in a neutralizing liquid at 40 ° C for 5 minutes, and then dried at 80 ° C for 15 minutes. If the resin composition layer of the present invention is used, the haloing distance Wb from the edge 150 of the via bottom 120 of the via hole 110 of the insulating layer 100 obtained in this way can be preferably 10 μm or less, more preferably 5 μm or less, even more preferably 4 μm or less, and particularly preferably 3 μm or less.

The halo distance Wb from the edge 150 of the via bottom 120 can be measured by using a FIB (focused ion beam) to cut away the insulating layer 100 so as to reveal a cross section that is parallel to the thickness direction of the insulating layer 100 and passes through the center 120C of the via bottom 120, and then observing the cross section with an electron microscope.

In addition, by using the resin composition layer of the present invention, the shape of the via hole 110 in the insulating layer 100 before the roughening treatment can be easily controlled, so that the shape of the via hole 110 can usually be easily controlled even in the insulating layer 100 after the roughening treatment. Therefore, even after the roughening treatment, the shape of the via hole 110 can be made as good as before the roughening treatment. Therefore, by using the resin composition layer of the present invention, a via hole 110 with a taper ratio Lb/Lt close to 100% can be realized in the insulating layer after the roughening treatment.

For example, the resin composition layer is heated at 100 ° C for 30 minutes, then heated at 180 ° C for 30 minutes to harden the insulating layer 100, and the insulating layer 100 is irradiated with _CO2 laser light under the conditions of a mask diameter of 1 mm, a pulse width of 16 μs, an energy of 0.2 mJ / shot, a shot number of 2, and a burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm ± 2 μm. Then, the insulating layer 100 is immersed in a swelling liquid at 60 ° C for 10 minutes, then immersed in an oxidizing agent solution at 80 ° C for 20 minutes, then immersed in a neutralizing liquid at 40 ° C for 5 minutes, and then dried at 80 ° C for 15 minutes. If the resin composition layer of the present invention is used, the taper ratio Lb / Lt of the via hole 110 formed in the insulating layer 100 obtained in this way can be preferably 76% to 100%, more preferably 80% to 100%, and particularly preferably 85% to 100%.

The taper ratio Lb/Lt of the via hole 110 can be calculated from the bottom diameter Lb and top diameter Lt of the via hole 110. The bottom diameter Lb and top diameter Lt of the via hole 110 can be measured by using a focused ion beam (FIB) to cut out the insulating layer 100 so that a cross section parallel to the thickness direction of the insulating layer 100 and passing through the center 120C of the via bottom 120 is revealed, and then observing the cross section with an electron microscope.

Furthermore, according to the study of the present inventor, it has been found that, in general, the larger the diameter of the via hole 110, the larger the size of the discoloration portion 140 tends to be, and therefore the size of the gap portion 160 tends to be larger. Therefore, the degree of suppression of the halo phenomenon can be evaluated by the ratio of the size of the gap portion 160 to the diameter of the via hole 110. For example, it can be evaluated by the halo ratio Hb to the bottom radius Lb/2 of the via hole 110. Here, the bottom radius Lb/2 of the via hole 110 refers to the radius of the via bottom 120 of the via hole 110. In addition, the halo ratio Hb to the bottom radius Lb/2 of the via hole 110 is the ratio obtained by dividing the halo distance Wb from the edge 150 of the via bottom 120 by the bottom radius Lb/2 of the via hole 110. The smaller the halo ratio Hb to the bottom radius Lb/2 of the via hole 110, the more effectively the halo phenomenon can be suppressed.

For example, the resin composition layer is heated at 100 ° C for 30 minutes, then heated at 180 ° C for 30 minutes to harden the insulating layer 100. The insulating layer 100 is irradiated with _CO2 laser light under the conditions of a mask diameter of 1 mm, a pulse width of 16 μs, an energy of 0.2 mJ / shot, a shot number of 2, and a burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm ± 2 μm. Then, the insulating layer 100 is immersed in a swelling liquid at 60 ° C for 10 minutes, then immersed in an oxidizing agent solution at 80 ° C for 20 minutes, then immersed in a neutralizing liquid at 40 ° C for 5 minutes, and then dried at 80 ° C for 15 minutes. If the resin composition layer of the present invention is used, the haloing ratio Hb of the via hole 110 formed in the insulating layer 100 thus obtained to the bottom radius Lb / 2 can be preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less.

The halo ratio Hb to the bottom radius Lb/2 of the via hole 110 can be calculated from the bottom diameter Lb of the via hole 110 and the halo distance Wb from the edge 150 of the via bottom 120 of the via hole 110.

Furthermore, by using the resin composition layer of the present invention, the formation of discolored portion 140 during the formation of via hole 110 can usually be suppressed. Therefore, as shown in FIG. 2, the size of discolored portion 140 can be reduced, and ideally, discolored portion 140 can be eliminated. The size of discolored portion 140 can be evaluated by the haloing distance Wt from edge 180 of via top 130 of via hole 110.

The edge 180 of the via top 130 corresponds to the inner peripheral edge of the discolored portion 140. The halo distance Wt from the edge 180 of the via top 130 represents the distance from the edge 180 of the via top 130 to the outer peripheral edge 190 of the discolored portion 140. It can be evaluated that the smaller the halo distance Wt from the edge 180 of the via top 130, the more effectively the formation of the discolored portion 140 can be suppressed.

For example, when an insulating layer 100 is obtained by heating a resin composition layer at 100°C for 30 minutes and then heating and curing it at 180°C for 30 minutes, and then irradiating the insulating layer 100 with _CO2 laser light under the conditions of a mask diameter of 1 mm, a pulse width of 16 μs, energy of 0.2 mJ/shot, number of shots of 2, and burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm±2 μm, the halo distance Wt from the edge 180 of the via top 130 can be preferably 6 μm or less, more preferably 5 μm or less.

The halo distance Wt from the edge 180 of the via top 130 can be measured by observation with an optical microscope.

Furthermore, according to the study by the inventor, it has been found that, in general, the larger the diameter of the via hole 110, the larger the size of the discolored portion 140 tends to be. Therefore, the degree of suppression of the formation of the discolored portion 140 can be evaluated by the ratio of the size of the discolored portion 140 to the diameter of the via hole 110. For example, the evaluation can be performed by the halo ratio Ht to the top radius Lt/2 of the via hole 110. Here, the top radius Lt/2 of the via hole 110 refers to the radius of the via top 130 of the via hole 110. In addition, the halo ratio Ht to the top radius Lt/2 of the via hole 110 is the ratio obtained by dividing the halo distance Wt from the edge 180 of the via top 130 by the top radius Lt/2 of the via hole 110. The smaller the halo ratio Ht to the top radius Lt/2 of the via hole 110, the more effectively the formation of the discolored portion 140 can be suppressed.

For example, when an insulating layer 100 obtained by heating a resin composition layer at 100°C for 30 minutes and then heating and curing it at 180°C for 30 minutes is irradiated with _CO2 laser light under conditions of a mask diameter of 1 mm, a pulse width of 16 μs, energy of 0.2 mJ/shot, number of shots of 2, and burst mode (10 kHz) to form a via hole 110 with a top diameter Lt of 30 μm ± 2 μm, the haloing ratio Ht of the via hole 110 to the top radius Lt/2 can be preferably 45% or less, more preferably 40% or less, and even more preferably 35% or less.

The halo ratio Ht of the via hole 110 to the top radius Lt/2 can be calculated from the top diameter Lt of the via hole 110 and the halo distance Wt from the edge 180 of the via top 130 of the via hole 110.

In the manufacturing process of the printed wiring board, the via hole 110 is usually formed without another conductor layer (not shown) being provided on the surface 100U of the insulating layer 100 opposite the conductor layer 210. Therefore, if the manufacturing process of the printed wiring board is understood, it is possible to clearly recognize the structure in which the via bottom 120 is on the conductor layer 210 side and the via top 130 is open on the opposite side of the conductor layer 210. However, in the completed printed wiring board, there may be cases where conductor layers are provided on both sides of the insulating layer 100. In this case, it may be difficult to distinguish the via bottom 120 and the via top 130 depending on the positional relationship with the conductor layer. However, usually, the top diameter Lt of the via top 130 is equal to or larger than the bottom diameter Lb of the via bottom 120. Therefore, in the above case, it is possible to distinguish the via bottom 120 and the via top 130 depending on the diameter size.

The inventors speculate that the mechanism by which the resin composition layer of the present invention provides the above-mentioned effects is as follows. However, the technical scope of the present invention is not limited by the mechanism described below.

Usually, when forming the via hole 110, energy such as heat or light is applied to the part of the insulating layer 100 where the via hole 110 is to be formed. A part of the energy applied at this time is transmitted to the periphery of the part where the via hole 110 is to be formed, and may deteriorate the resin. When the resin deteriorates in this way, the insulating layer discolors in the deteriorated part and becomes more susceptible to erosion. Therefore, the erosion during the roughening treatment causes a haloing phenomenon, and the insulating layer may peel off from the conductor layer. In contrast, in the resin composition layer of the present invention, the resin composition can effectively absorb energy due to the action of the colorant (D). In particular, the resin composition has a significantly improved absorption performance against a wide variety of laser beams used industrially due to the action of the colorant (D). Therefore, the applied energy is efficiently absorbed by the resin composition, and the energy delivered to the via bottom 120 can be prevented from becoming excessive, so that resin deterioration around the via bottom 120 can be suppressed. Therefore, the insulating layer 100 obtained using the resin composition layer of the present invention can suppress the haloing phenomenon.

Also, as can be seen from the explanation of the average particle size and the specific surface area, the particle size of the (C) component contained in the resin composition layer is usually small. Because the particle size of the (C) component is small, the energy given to the insulating layer 100 can be transmitted well in the thickness direction of the insulating layer 100. For example, when thermal energy or light energy is given to the surface 100U of the insulating layer 100, the energy can be transmitted effectively in the thickness direction without significant diffusion in the in-plane direction. Therefore, a via hole 110 with a large taper rate can be easily formed, and the shape of the via hole 110 can be improved.

[11. Uses of resin composition layer]
The resin composition layer of the present invention can be suitably used as a resin composition layer for insulating purposes. Specifically, the resin composition layer of the present invention can be suitably used as a resin composition layer for forming an insulating layer of a printed wiring board (resin composition layer for forming an insulating layer of a printed wiring board), and can be more suitably used as a resin composition layer for forming an interlayer insulating layer of a printed wiring board (resin composition layer for forming an interlayer insulating layer of a printed wiring board). In addition, the resin composition layer of the present invention can be suitably used as a resin composition layer for forming an insulating layer for forming a conductor layer (including a rewiring layer) on an insulating layer (resin composition layer for forming an insulating layer for forming a conductor layer).

In particular, from the viewpoint of effectively utilizing the advantages of being able to suppress the haloing phenomenon and being able to form via holes with good shapes, the resin composition layer is suitable as a resin composition layer for forming an insulating layer having via holes (a resin composition layer for forming an insulating layer having via holes), and is particularly suitable as a resin composition layer for forming an insulating layer having via holes with a top diameter of 35 μm or less.

[12. Resin sheet]
The resin sheet of the present invention includes a support and a layer of the resin composition of the present invention provided on the support.

Examples of the support include films made of plastic materials, metal foils, and release paper, with films made of plastic materials and metal foils being preferred.

When a film made of a plastic material is used as the support, examples of the plastic material include polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as "PET") and polyethylene naphthalate (hereinafter sometimes abbreviated as "PEN"), polycarbonate (hereinafter sometimes abbreviated as "PC"), acrylic polymers such as polymethyl methacrylate (hereinafter sometimes abbreviated as "PMMA"), cyclic polyolefins, triacetyl cellulose (hereinafter sometimes abbreviated as "TAC"), polyether sulfide (hereinafter sometimes abbreviated as "PES"), polyether ketone, polyimide, etc. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

When a metal foil is used as the support, examples of the metal foil include copper foil and aluminum foil, with copper foil being preferred. As the copper foil, a foil made of a single metal, copper, or an alloy of copper and another metal (e.g., tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

The support may be subjected to a matte treatment, corona treatment, antistatic treatment, etc. on the surface that is to be bonded to the resin composition layer.

As the support, a support with a release layer having a release layer on the surface to be bonded to the resin composition layer may be used. Examples of the release agent used in the release layer of the support with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. The support with a release layer may be a commercially available product, such as "SK-1", "AL-5", and "AL-7" manufactured by Lintec Corporation, "Lumirror T60" manufactured by Toray Industries, Inc., "Purex" manufactured by Teijin Limited, and "Unipeel" manufactured by Unitika Limited, which are PET films having a release layer mainly composed of an alkyd resin-based release agent.

The thickness of the support is not particularly limited, but is preferably in the range of 5 μm to 75 μm, and more preferably in the range of 10 μm to 60 μm. When using a support with a release layer, it is preferable that the thickness of the entire support with the release layer is in the above range.

The resin sheet may also contain any layer other than the support and the resin composition layer, as necessary. Examples of such optional layers include a protective film similar to the support that is provided on the surface of the resin composition layer that is not bonded to the support (i.e., the surface opposite the support). The thickness of the protective film is not particularly limited, but is, for example, 1 μm to 40 μm. The protective film can prevent the adhesion of dirt and the like to the surface of the resin composition layer and scratches.

The resin sheet can be produced, for example, by preparing a resin varnish containing an organic solvent and a resin composition, applying the resin varnish onto a support using a coating device such as a die coater, and then drying the varnish to form a resin composition layer.

Examples of organic solvents include ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; acetate ester solvents such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitol solvents such as cellosolve and butyl carbitol; aromatic hydrocarbon solvents such as toluene and xylene; amide solvents such as dimethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone; and the like. The organic solvents may be used alone or in combination of two or more.

Drying may be performed by heating, blowing hot air, or other methods. There are no particular limitations on the drying conditions, but drying is generally performed so that the content of organic solvent in the resin composition layer is 10% by mass or less, and preferably 5% by mass or less. Although this varies depending on the boiling point of the organic solvent in the resin varnish, for example, when using a resin varnish containing 30% by mass to 60% by mass of organic solvent, the resin composition layer can be formed by drying at 50°C to 150°C for 3 to 10 minutes.

The resin sheet can be stored in a roll. If the resin sheet has a protective film, it can usually be used by peeling off the protective film.

[13. Printed Wiring Board]
The printed wiring board of the present invention includes an insulating layer formed of a cured product of a thin resin composition layer as described above. In addition, this insulating layer can suppress the haloing phenomenon and can form a via hole with a good shape. Therefore, by using the resin composition layer of the present invention, it is possible to achieve a thin printed wiring board while suppressing the deterioration of performance due to the haloing phenomenon or the deterioration of the shape of the via hole.

The via hole is usually provided to provide electrical continuity between the conductor layers provided on both sides of the insulating layer having the via hole. Thus, the printed wiring board of the present invention usually includes a first conductor layer, a second conductor layer, and an insulating layer formed between the first conductor layer and the second conductor layer. Then, a via hole is formed in the insulating layer, and the first conductor layer and the second conductor layer can be electrically connected through the via hole.

By utilizing the advantages of the resin composition layer, such as the ability to suppress the haloing phenomenon and the ability to form via holes with a good shape, it is possible to realize a specific printed wiring board that has been difficult to realize in the past. This specific printed wiring board is a printed wiring board that includes a first conductor layer, a second conductor layer, and an insulating layer formed between the first conductor layer and the second conductor layer, and satisfies all of the following requirements (i) to (v).
(i) The thickness of the insulating layer is 15 μm or less.
(ii) The insulating layer has a via hole with a top diameter of 35 μm or less.
(iii) The taper ratio of the via hole is 80% or more.
(iv) The halo distance from the edge of the via bottom of the via hole is 5 μm or less.
(v) The haloing ratio to the bottom radius of the via hole is 35% or less.

The specific printed wiring board will be described below with reference to the drawings. FIG. 4 is a schematic cross-sectional view of a printed wiring board 300 according to a second embodiment of the present invention. FIG. 4 shows a cross-section of the printed wiring board 300 cut along a plane that passes through the center 120C of the via bottom 120 of the via hole 110 and is parallel to the thickness direction of the insulating layer 100. In FIG. 4, parts corresponding to the elements shown in FIGS. 1 to 3 are indicated with the same reference numerals as those used in FIGS. 1 to 3.

As shown in FIG. 4, the specific printed wiring board 300 according to the second embodiment of the present invention includes a first conductor layer 210, a second conductor layer 220, and an insulating layer 100 formed between the first conductor layer 210 and the second conductor layer 220. A via hole 110 is formed in the insulating layer 100. Also, the second conductor layer 220 is usually provided after the via hole 110 is formed. Therefore, the second conductor layer 220 is usually formed not only on the surface 100U of the insulating layer 100 but also in the via hole 110, and the first conductor layer 210 and the second conductor layer 220 are electrically connected through the via hole 110.

The thickness T of the insulating layer 100 included in the specific printed wiring board 300 is usually 15 μm or less, preferably 12 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. Since the specific printed wiring board 300 has such a thin insulating layer 100, the specific printed wiring board 300 itself can be made thinner. The lower limit of the thickness T of the insulating layer 100 is preferably 1 μm or more, more preferably 2 μm or more, and particularly preferably 3 μm or more, from the viewpoint of increasing the insulating performance of the insulating layer 100. Here, the thickness T of the insulating layer 100 represents the dimension of the insulating layer 100 between the first conductor layer 210 and the second conductor layer 220, and does not represent the dimension of the insulating layer 100 at a position where the first conductor layer 210 or the second conductor layer 220 is not present. The thickness T of the insulating layer 100 usually corresponds to the distance between the main surface 210U of the first conductor layer 210 and the main surface 220D of the second conductor layer 220, which face each other through the insulating layer 100, and also corresponds to the depth of the via hole 110.

The top diameter Lt of the via hole 110 in the insulating layer 100 included in the specific printed wiring board 300 is usually 35 μm or less, preferably 33 μm or less, and particularly preferably 32 μm or less. Since the specific printed wiring board 300 includes an insulating layer 100 having a via hole 110 with a small top diameter Lt, it is possible to promote the miniaturization of wiring including the first conductor layer 210 and the second conductor layer 220. From the viewpoint of easily forming the via hole 110, the lower limit of the top diameter Lt of the via hole 110 is preferably 3 μm or more, more preferably 10 μm or more, and particularly preferably 15 μm or more.

The taper ratio Lb/Lt (%) of the via hole 110 in the insulating layer 100 included in the specific printed wiring board 300 is usually 80% to 100%. The specific printed wiring board 300 includes an insulating layer 100 having a via hole 110 with a good shape and a high taper ratio Lb/Lt. Therefore, the specific printed wiring board 300 can usually increase the reliability of the conduction between the first conductor layer 210 and the second conductor layer 220.

The halo distance Wb from the edge 150 of the via bottom 120 of the via hole 110 of the insulating layer 100 included in the specific printed wiring board 300 is usually 5 μm or less, preferably 4 μm or less, and more preferably 3 μm or less. The specific printed wiring board 300 has such a small halo distance Wb from the edge 150 of the via bottom 120, and therefore the peeling of the insulating layer 100 from the first conductor layer 210 is small. Therefore, the specific printed wiring board 300 can usually increase the reliability of the conduction between the first conductor layer 210 and the second conductor layer 220.

The halo ratio Hb of the via hole 110 of the insulating layer 100 included in the specific printed wiring board 300 to the bottom radius Lb/2 is usually 35% or less, preferably 30% or less, and more preferably 25% or less. The specific printed wiring board 300 has such a small halo ratio Hb to the bottom radius Lb/2, and therefore the peeling of the insulating layer 100 from the first conductor layer 210 is small. The specific printed wiring board 300 including the insulating layer 100 having such a small halo ratio Hb can usually increase the reliability of the conduction between the first conductor layer 210 and the second conductor layer 220. The lower limit of the halo ratio Hb to the bottom radius Lb/2 is ideally zero, but is usually 5% or more.

The number of via holes 110 in the insulating layer 100 included in the specific printed wiring board 300 may be one or two or more. When the insulating layer 100 has two or more via holes 110, some of them may satisfy requirements (ii) to (v), but it is preferable that all of them satisfy requirements (ii) to (v). Also, for example, it is preferable that five via holes 110 randomly selected from the insulating layer 100 satisfy requirements (ii) to (v) on average.

The specific printed wiring board 300 described above can be realized by forming an insulating layer 100 from the cured product of the resin composition layer of the present invention. In this case, the planar shape of the via bottom 120 and the via top 130 of the via hole 110 formed in the insulating layer 100 can be any shape, but is usually circular or elliptical, and preferably circular.

A printed wiring board such as a specific printed wiring board can be produced, for example, by using a resin sheet and carrying out a production method including the following steps (I) to (IV).
(I) A step of laminating a resin sheet on an inner layer substrate such that the resin composition layer is bonded to the inner layer substrate.
(II) A step of thermally curing the resin composition layer to form an insulating layer.
(III) forming a via hole in the insulating layer.
(IV) A step of subjecting the insulating layer to a roughening treatment.

The "inner layer substrate" used in step (I) is a member that will become the substrate of the printed wiring board. Examples of inner layer substrates include glass epoxy substrates, metal substrates, polyester substrates, polyimide substrates, BT resin substrates, and thermosetting polyphenylene ether substrates. In general, inner layer substrates have a conductor layer on one or both sides. An insulating layer is formed on the conductor layer. This conductor layer may be patterned, for example, to function as a circuit. An inner layer substrate in which a conductor layer is formed as a circuit on one or both sides of the substrate is sometimes called an "inner layer circuit substrate." In addition, intermediate products on which an insulating layer and/or a conductor layer is to be further formed during the manufacture of a printed wiring board are also included in the "inner layer substrate." When the printed wiring board is a component-embedded circuit board, an inner layer substrate with a component embedded may be used.

The lamination of the inner layer substrate and the resin sheet can be performed, for example, by bonding the resin sheet to the inner layer substrate from the support side, thereby laminating the resin composition layer to the inner layer substrate. Examples of the member for bonding the resin sheet to the inner layer substrate by heat and pressure (hereinafter sometimes referred to as the "heat and pressure bonding member") include a heated metal plate (such as a SUS panel) or a metal roll (SUS roll). It is preferable to press the heat and pressure bonding member not directly onto the resin sheet, but via an elastic material such as heat-resistant rubber so that the resin sheet can sufficiently follow the surface irregularities of the inner layer substrate.

The lamination of the inner layer substrate and the resin sheet may be performed, for example, by a vacuum lamination method. In the vacuum lamination method, the heat-pressure bonding temperature is preferably in the range of 60°C to 160°C, more preferably in the range of 80°C to 140°C, the heat-pressure bonding pressure is preferably in the range of 0.098MPa to 1.77MPa, more preferably in the range of 0.29MPa to 1.47MPa, and the heat-pressure bonding time is preferably in the range of 20 seconds to 400 seconds, more preferably in the range of 30 seconds to 300 seconds. The lamination is preferably performed under reduced pressure conditions of a pressure of 26.7hPa or less.

Lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include a vacuum pressure laminator manufactured by Meiki Seisakusho Co., Ltd., a vacuum applicator manufactured by Nikko Materials Co., Ltd., and a batch-type vacuum pressure laminator.

After lamination, the laminated resin sheets may be smoothed under normal pressure (atmospheric pressure), for example, by pressing the support side with a heat-pressure bonding member. The pressing conditions for the smoothing treatment may be the same as the heat-pressure bonding conditions for the lamination. The smoothing treatment may be performed using a commercially available laminator. Note that lamination and smoothing treatment may be performed consecutively using the commercially available vacuum laminator described above.

In step (II), the resin composition layer is thermally cured to form an insulating layer. The thermal curing conditions for the resin composition layer are not particularly limited, and any of the conditions employed when forming an insulating layer for a printed wiring board may be used.

For example, the thermal curing conditions for the resin composition layer vary depending on the type of resin composition, but the curing temperature is usually in the range of 120°C to 240°C (preferably in the range of 150°C to 220°C, more preferably in the range of 170°C to 200°C), and the curing time is usually in the range of 5 minutes to 120 minutes (preferably in the range of 10 minutes to 100 minutes, more preferably in the range of 15 minutes to 90 minutes).

Before the resin composition layer is thermally cured, the resin composition layer may be preheated at a temperature lower than the curing temperature. For example, prior to thermally curing the resin composition layer, the resin composition layer may be preheated at a temperature of typically 50°C or higher and lower than 120°C (preferably 60°C or higher and 115°C or lower, more preferably 70°C or higher and 110°C or lower), typically for 5 minutes or more (preferably 5 minutes to 150 minutes, more preferably 15 minutes to 120 minutes, and even more preferably 15 minutes to 100 minutes).

In step (III), a via hole is formed in the insulating layer. Methods for forming the via hole include irradiation with laser light, etching, mechanical drilling, and the like. Among these, irradiation with laser light is generally prone to causing the haloing phenomenon. Therefore, from the viewpoint of effectively utilizing the effect of suppressing the haloing phenomenon, irradiation with laser light is preferred.

The irradiation of the laser light can be carried out, for example, by using a laser processing machine having a laser light source such as a carbon dioxide laser, a YAG laser, an excimer laser, etc. Examples of laser processing machines that can be used include the _CO2 laser processing machine "LC-2k212/2C" manufactured by Via Mechanics, the 605GTWIII(-P) manufactured by Mitsubishi Electric Corporation, and a laser processing machine manufactured by Matsushita Welding Systems Co., Ltd.

The conditions for irradiating the laser light, such as the wavelength, number of pulses, pulse width, and output, are not particularly limited, and appropriate conditions may be set according to the type of laser light source. In addition, from the viewpoint of significantly obtaining the desired effect of the present invention, it is preferable that the wavelength of the laser light is within the range of the absorption wavelength of the colorant (D).

In step (IV), the insulating layer is subjected to a roughening treatment. The procedure and conditions of the roughening treatment are not particularly limited, and any procedure and conditions used in forming an insulating layer of a printed wiring board can be adopted. For example, the insulating layer can be roughened by carrying out a swelling treatment using a swelling liquid, a roughening treatment using an oxidizing agent, and a neutralization treatment using a neutralizing liquid in this order.

The swelling liquid is not particularly limited, but examples thereof include an alkaline solution, a surfactant solution, and the like, and is preferably an alkaline solution. As the alkaline solution, a sodium hydroxide solution and a potassium hydroxide solution are more preferable. Examples of commercially available swelling liquids include "Swelling Dip Securigans P" and "Swelling Dip Securigans SBU" manufactured by Atotech Japan. In addition, the swelling liquid may be used alone or in combination of two or more types in any ratio. The swelling treatment using the swelling liquid is not particularly limited, but may be performed by, for example, immersing the insulating layer in a swelling liquid at 30°C to 90°C for 1 to 20 minutes. From the viewpoint of suppressing the swelling of the resin of the insulating layer to an appropriate level, it is preferable to immerse the insulating layer in a swelling liquid at 40°C to 80°C for 5 to 15 minutes.

The oxidizing agent is not particularly limited, but examples thereof include alkaline permanganate solutions in which potassium permanganate or sodium permanganate is dissolved in an aqueous solution of sodium hydroxide. The oxidizing agent may be used alone or in combination of two or more types in any ratio. The roughening treatment using an oxidizing agent such as an alkaline permanganate solution is preferably performed by immersing the insulating layer in an oxidizing agent solution heated to 60°C to 80°C for 10 minutes to 30 minutes. The concentration of permanganate in the alkaline permanganate solution is preferably 5% by mass to 10% by mass. Examples of commercially available oxidizing agents include alkaline permanganate solutions such as "Concentrate Compact CP" and "Dosing Solution Securigans P" manufactured by Atotech Japan.

The neutralizing liquid is preferably an acidic aqueous solution, and a commercially available product is, for example, "Reduction Solution Securigant P" manufactured by Atotech Japan. The neutralizing liquid may be used alone or in combination of two or more types in any ratio. Treatment with the neutralizing liquid can be performed by immersing the treated surface that has been roughened with an oxidizing agent in a neutralizing liquid at 30°C to 80°C for 5 to 30 minutes. From the viewpoint of workability, etc., a method in which the object that has been roughened with an oxidizing agent is immersed in a neutralizing liquid at 40°C to 70°C for 5 to 20 minutes is preferred.

The support may be removed between steps (I) and (II), between steps (II) and (III), between steps (III) and (IV), or after step (IV). In particular, from the viewpoint of further suppressing the occurrence of gouged portions, it is preferable to remove the support after step (III) of forming via holes in the insulating layer. For example, if the support is peeled off after forming via holes in the insulating layer by irradiating with laser light, it is easy to form via holes with a good shape.

The method for manufacturing a printed wiring board may further include a step (V) of forming a conductor layer. This step (V) may be carried out according to various methods used in the manufacture of printed wiring boards.

Step (V) is a step of forming a conductor layer. The conductor material used for the conductor layer is not particularly limited. In a preferred embodiment, the conductor layer contains one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The conductor layer may be a single metal layer or an alloy layer. Examples of the alloy layer include layers formed from alloys of two or more metals selected from the above group (e.g., nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy). Among them, from the viewpoints of versatility of conductor layer formation, cost, ease of patterning, etc., a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper; or an alloy layer of nickel-chromium alloy, copper-nickel alloy, or copper-titanium alloy; is preferable. Furthermore, a single metal layer of chromium, nickel, titanium, aluminum, zinc, gold, palladium, silver, or copper; or an alloy layer of nickel-chromium alloy; is more preferable, and a single metal layer of copper is particularly preferable.

The conductor layer may be a single-layer structure, or a multi-layer structure including two or more single metal layers or alloy layers made of different types of metals or alloys. When the conductor layer is a multi-layer structure, the layer in contact with the insulating layer is preferably a single metal layer of chromium, zinc, or titanium, or an alloy layer of a nickel-chromium alloy.

The thickness of the conductor layer depends on the desired printed wiring board design, but is generally between 3 μm and 35 μm, preferably between 5 μm and 30 μm.

The conductor layer may be formed by plating. For example, the surface of the insulating layer may be plated using a technique such as a semi-additive method or a full-additive method to form a conductor layer having a desired wiring pattern. Among these, from the viewpoint of ease of production, it is preferable to form the conductor layer using a semi-additive method.

Below, an example of forming a conductor layer by the semi-additive method is shown. First, a plating seed layer is formed on the surface of an insulating layer by electroless plating. Next, a mask pattern is formed on the formed plating seed layer to expose a part of the plating seed layer corresponding to the desired wiring pattern. After that, a metal layer is formed on the exposed plating seed layer by electrolytic plating, and the mask pattern is removed. Thereafter, unnecessary plating seed layer is removed by etching or the like, and a conductor layer having the desired wiring pattern can be formed.

If necessary, the formation of insulating layers and conductor layers through steps (I) to (V) may be repeated to produce a multilayer printed wiring board.

[14. Semiconductor Device]
The semiconductor device of the present invention includes the above-mentioned printed wiring board. This semiconductor device can be manufactured using the printed wiring board.

Semiconductor devices include various semiconductor devices used in electrical appliances (e.g., computers, mobile phones, digital cameras, and televisions) and vehicles (e.g., motorcycles, automobiles, trains, ships, and aircraft).

A semiconductor device can be manufactured, for example, by mounting a component (semiconductor chip) on a conductive point on a printed wiring board. A "conductive point" is a "point on a printed wiring board that transmits an electrical signal," and the location can be either on the surface or embedded. In addition, the semiconductor chip can be any electrical circuit element made of semiconductor material.

The method of mounting semiconductor chips when manufacturing a semiconductor device is not particularly limited as long as the semiconductor chip functions effectively. Examples of mounting methods include wire bonding mounting, flip chip mounting, bumpless buildup layer (BBUL) mounting, anisotropic conductive film (ACF) mounting, non-conductive film (NCF) mounting, etc. Here, "bumpless buildup layer (BBUL) mounting" refers to "a mounting method in which a semiconductor chip is directly embedded in a recess in a printed wiring board and the semiconductor chip is connected to the wiring on the printed wiring board."

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the following examples. In the following description, "parts" and "%" representing amounts mean "parts by mass" and "% by mass", respectively, unless otherwise specified. Furthermore, the operations described below were carried out in an environment of normal temperature and pressure, unless otherwise specified.

[Explanation of inorganic filler]
<Method for measuring average particle size of inorganic filler>
100 mg of inorganic filler, 0.1 g of dispersant ("SN9228" manufactured by San Nopco) and 10 g of methyl ethyl ketone were weighed into a vial and dispersed by ultrasonic waves for 20 minutes. Using a laser diffraction particle size distribution measuring device ("SALD-2200" manufactured by Shimadzu Corporation), the particle size distribution of the inorganic filler was measured on a volume basis by a batch cell method. Then, from the obtained particle size distribution, the average particle size of the inorganic filler was calculated as the median diameter.

<Method for measuring the specific surface area of inorganic filler>
The specific surface area of the inorganic filler was measured using a BET fully automatic specific surface area measuring device ("Macsorb HM-1210" manufactured by Mountec Co., Ltd.).

<Inorganic filler 1>
Inorganic filler 1 was prepared by surface-treating 100 parts of spherical silica (UFP-30 manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 0.078 μm, specific surface area 30.7 m ² /g) with 2 parts of N-phenyl-3-aminopropyltrimethoxysilane (KBM573 manufactured by Shin-Etsu Chemical Co., Ltd.).

<Inorganic filler 2>
100 parts of spherical silica ("SC2500SQ" manufactured by Admatechs, average particle size 0.77 μm, specific surface area 5.9 m ² /g) was surface-treated with 1 part of N-phenyl-3-aminopropyltrimethoxysilane (KBM573 manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare inorganic filler 2.

[Example 1. Preparation of resin composition 1]
6 parts of bixylenol type epoxy resin ("YX4000HK" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 185), 5 parts of naphthalene type epoxy resin ("ESN475V" manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., epoxy equivalent of about 332), 15 parts of bisphenol AF type epoxy resin ("YL7760" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 238), 2 parts of cyclohexane type epoxy resin ("ZX1658GS" manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of about 135), and 2 parts of phenoxy resin ("YL7500BH30" manufactured by Mitsubishi Chemical Corporation, 1:1 solution of cyclohexanone:methyl ethyl ketone (MEK) with 30% by mass of non-volatile components, Mw = 44000) were dissolved in a mixed solvent of 20 parts of solvent naphtha and 10 parts of cyclohexanone with stirring. The resulting solution was cooled to room temperature. Thereafter, this solution was mixed with 6 parts of an active ester curing agent (DIC Corporation "EXB-8000L-65TM", active group equivalent of about 220, toluene with 65% by mass of nonvolatile components: 1:1 solution of MEK), 4 parts of a triazine skeleton-containing cresol novolac curing agent (DIC Corporation "LA-3018-50P", hydroxyl group equivalent of about 151, 2-methoxypropanol solution with 50% nonvolatile components), 50 parts of inorganic filler 1, 1 part of carbon black as a black pigment (Nippon Pigment Co., Ltd. "NV-7-201"), and 0.05 parts of an amine curing accelerator (4-dimethylaminopyridine (DMAP)). The mixture was uniformly dispersed in a high-speed rotating mixer to obtain a mixture. This mixture was filtered with a cartridge filter (ROKITECHNO Corporation "SHP020") to obtain a resin composition 1.

[Example 2. Preparation of resin composition 2]
A blue pigment ("Cyanine Blue 4920" manufactured by Dainichi Seika Chemicals Co., Ltd.) was used instead of carbon black. Resin composition 2 was prepared by carrying out the same procedure as in the preparation of resin composition 1 except for the above.

[Comparative Example 1. Preparation of Resin Composition 3]
Resin composition 3 was prepared in the same manner as in the preparation of resin composition 1, except for the above-mentioned points, in which carbon black was not used.

[Comparative Example 2. Preparation of Resin Composition 4]
Inorganic filler 2 was used instead of inorganic filler 1. Resin composition 4 was prepared in the same manner as in the preparation of resin composition 1 except for the above.

[Composition of Resin Composition]
The components used in the preparation of Resin Compositions 1 to 5 and their blend amounts (parts by mass of non-volatile content) are shown in the following Table 1. The abbreviations in the following table are as follows.
Hardener content: the ratio of the hardener content to 100 mass% of the resin component in the resin composition.
Content of active ester-based curing agent: The content ratio of the active ester-based curing agent to 100% by mass of the resin component in the resin composition.
Content of inorganic filler: The ratio of the content of the inorganic filler to 100% by mass of the non-volatile components in the resin composition.
Pigment content: The ratio of the pigment content to 100% by mass of the non-volatile components in the resin composition.

[Preparation of resin sheet]
As a support, a polyethylene terephthalate film ("Lumirror R80" manufactured by Toray Industries, Inc., thickness 38 μm, softening point 130° C.) that had been subjected to a release treatment with an alkyd resin-based release agent ("AL-5" manufactured by Lintec Corporation) was prepared.

Each of resin compositions 1 to 4 was uniformly applied to the support using a die coater so that the thickness of the resin composition layer after drying was 10 μm, and then dried at 70°C to 95°C for 2 minutes to form a resin composition layer on the support. Next, the rough surface of a polypropylene film (Oji F-Tex Co., Ltd. "Alphan MA-411", thickness 15 μm) was attached as a protective film to the surface of the resin composition layer that was not joined to the support. This resulted in a resin sheet A having a support, a resin composition layer, and a protective film in this order.

[Thickness measurement method]
The thickness of the resin composition layer and other layers was measured using a contact type film thickness meter ("MCD-25MJ" manufactured by Mitutoyo Corporation).

[Evaluation of via holes after laser via processing]
Using resin sheets A produced using each of resin compositions 1 to 4, insulating layers having via holes were formed by the following method, and the via holes were evaluated.

<Preparation of evaluation samples>
(1) Preparation of inner layer board:
As an inner layer substrate, a glass cloth-based epoxy resin double-sided copper-clad laminate having copper foil layers on both sides (copper foil thickness 3 μm, substrate thickness 0.15 mm, Mitsubishi Gas Chemical Company's "HL832NSF LCA", 255×340 mm size) was prepared.

(2) Lamination of resin sheet:
The protective film was peeled off from the resin sheet A to expose the resin composition layer. Using a batch type vacuum pressure laminator (two-stage build-up laminator "CVP700" manufactured by Nikko Materials Co., Ltd.), the resin composition layer was laminated on both sides of the inner layer substrate so that it was in contact with the inner layer substrate. The lamination was performed by reducing the pressure for 30 seconds to adjust the air pressure to 13 hPa or less, and then pressing at 130°C and a pressure of 0.74 MPa for 45 seconds. Next, a heat press was performed at 120°C and a pressure of 0.5 MPa for 75 seconds.

(3) Thermal curing of resin composition layer:
Thereafter, the inner layer substrate laminated with the resin sheet was placed in an oven at 100° C. and heated for 30 minutes, and then transferred to an oven at 180° C. and heated for 30 minutes to thermally cure the resin composition layer and form an insulating layer. The insulating layer had a thickness of 10 μm. The support was then peeled off to obtain a cured substrate A having an insulating layer, an inner layer substrate, and an insulating layer in this order.

(4) Laser via processing:
Using a _CO2 laser processing machine (Mitsubishi Electric Corporation "605GTWIII (-P)"), the insulating layer was irradiated with laser light to form a plurality of via holes with a top diameter of about 30 μm in the insulating layer. The laser light irradiation conditions were mask diameter 1 mm, pulse width 16 μs, energy 0.2 mJ/shot, number of shots 2, and burst mode (10 kHz). The cured substrate A with via holes formed in the insulating layer in this way is called via-processed substrate A.

(5) Roughening treatment:
A desmear treatment as a roughening treatment was performed on the via-processed substrate A. As the desmear treatment, the following wet desmear treatment was performed.

(Wet desmear treatment)
The via-processed substrate A was immersed in a swelling liquid (Atotech Japan's "Swelling Dip Securigant P", an aqueous solution of diethylene glycol monobutyl ether and sodium hydroxide) at 60° C. for 10 minutes, then immersed in an oxidizing agent solution (Atotech Japan's "Concentrate Compact CP", an aqueous solution of potassium permanganate at about 6% and sodium hydroxide at about 4%) at 80° C. for 20 minutes, then immersed in a neutralizing liquid (Atotech Japan's "Reduction Solution Securigant P", an aqueous solution of sulfuric acid) at 40° C. for 5 minutes, and then dried at 80° C. for 15 minutes. The via-processed substrate A subjected to this wet desmear treatment is called a roughened substrate A.

<Measurement of via hole dimensions before roughening treatment>
The cross section of the via-processed substrate A before the roughening treatment was observed using a FIB-SEM composite device ("SMI3050SE" manufactured by SII NanoTechnology). In detail, the insulating layer was cut out using a FIB (focused ion beam) so that a cross section parallel to the thickness direction of the insulating layer and passing through the center of the via bottom of the via hole appeared. This cross section was observed using a SEM (scanning electron microscope). The top and bottom diameters of the via hole were measured from the observed image.

The above measurements were performed on five randomly selected via holes. The average of the top diameters of the five measured via holes was used as the top diameter Lt1 of the sample before the roughening treatment. The average of the bottom diameters of the five measured via holes was used as the bottom diameter Lb1 of the sample before the roughening treatment.

<Measurement of via hole dimensions and halo distance after roughening treatment>
The roughened substrate A was observed in cross section using a FIB-SEM composite device ("SMI3050SE" manufactured by SII Nano Technology Co., Ltd.). In detail, the insulating layer was cut out using a FIB (focused ion beam) so that a cross section parallel to the thickness direction of the insulating layer and passing through the center of the via bottom of the via hole appeared. This cross section was observed by SEM. From the observed image, the bottom diameter and top diameter of the via hole were measured. In addition, in the image observed by SEM, a gap portion formed by the insulating layer peeling off from the copper foil layer of the inner layer substrate was seen, continuing from the edge of the via bottom. Therefore, from the observed image, the distance r3 from the center of the via bottom to the edge of the via bottom (corresponding to the inner radius of the gap) and the distance r4 from the center of the via bottom to the end on the far side of the gap (corresponding to the outer radius of the gap) were measured, and the difference r4-r3 between these distances r3 and r4 was calculated as the haloing distance from the edge of the via bottom at that measurement point.

The above measurements were performed on five randomly selected via holes. The average of the top diameters of the five measured via holes was used as the top diameter Lt2 of the sample after roughening treatment. The average of the bottom diameters of the five measured via holes was used as the bottom diameter Lb2 of the sample after roughening treatment. The average of the halo distances of the five measured via holes was used as the halo distance Wb from the edge of the via bottom of the sample.

[result]
The evaluation results of the above-mentioned Examples and Comparative Examples are shown in Table 2 below.
In Table 2, the taper ratio represents the ratio "Lb1/Lt1" of the top diameter Lt1 to the bottom diameter Lb1 of the via hole before the roughening treatment.

In Table 2, the halo ratio Hb represents the ratio "Wb/(Lb/2)" of the halo distance Wb from the edge of the via bottom after roughening treatment to the radius (Lb/2) of the via bottom of the via hole after roughening treatment. If this halo ratio Hb is 35% or less, it is judged as "good", and if the halo ratio Ht is greater than 35%, it is judged as "poor".

[Consider]
As can be seen from Table 2, in the examples, a via hole with a large taper ratio can be formed in an insulating layer, even though the insulating layer is formed using a thin resin composition layer with a thickness of 10 μm. From this result, it was confirmed that the resin composition layer of the present invention can realize an insulating layer capable of forming a via hole with a good shape even if it is thin.

As can be seen from Table 2, in the examples, the insulating layer was formed using a thin resin composition layer with a thickness of 10 μm, but the haloing ratio Hb after roughening treatment was small. From these results, it was confirmed that the resin composition layer of the present invention can realize an insulating layer that can suppress the haloing phenomenon even if it is thin.

In particular, an insulating layer having a thickness of 15 μm or less, a via hole top diameter Lt of 35 μm or less, a via hole taper rate of 80% or more, a halo distance Wb from the edge of the bottom of the via hole of 5 μm or less, and a halo ratio Hb to the bottom radius of the via hole of 35% or less, as obtained in Examples 1 and 2, has not been realized in the past. Therefore, the realization of such an insulating layer has significant technical significance in recent printed wiring boards, where thinner insulating layers are desired.

Although Examples 1 and 2 do not show specific results when a conductor layer is formed on the insulating layer of the roughened substrate A, by looking at the results of the above-mentioned examples, a person skilled in the art can clearly understand that a specific printed wiring board that satisfies requirements (i) to (v) can be obtained by forming a conductor layer on the insulating layer of the roughened substrate A.
In addition, it has been confirmed that even when components (E) and (F) are not contained in Examples 1 and 2, the results are similar to those of the above Examples, although to a different extent.

100 Insulating layer 100U Surface of insulating layer opposite to conductor layer 110 Via hole 120 Via bottom 120C Center of via bottom 130 Via top 140 Discolored portion 150 Edge of via bottom of via hole 160 Gap portion 170 End portion on outer periphery of gap portion 180 Edge of via top of via hole 190 Edge portion on outer periphery of discolored portion 200 Inner layer substrate 210 Conductive layer (first conductor layer)
220 Second conductor layer 300 Printed wiring board Lb Bottom diameter of via hole Lt Top diameter of via hole T Thickness of insulating layer Wt Halo distance from edge of via top Wb Halo distance from edge of via bottom

Claims (16)

A resin composition layer having a thickness of 15 μm or less containing a resin composition,
The resin composition comprises (A) an epoxy resin, (B) a curing agent, (C) an inorganic filler having an average particle size of 100 nm or less or a specific surface area measured by a BET method of 15 m ² /g or more, and (D) a colorant;
(B) A resin composition layer, in which the curing agent contains a phenol-based curing agent and an active ester-based curing agent. The resin composition layer according to claim 1, wherein the inorganic filler (C) has an average particle size of 100 nm or less. The resin composition layer according to claim 1 , wherein the inorganic filler (C) has a specific surface area of 15 m ² /g or more as measured by a BET method. The resin composition layer according to any one of claims 1 to 3, wherein the amount of (C) inorganic filler is 30% by mass or more relative to 100% by mass of the non-volatile components in the resin composition. The resin composition layer according to any one of claims 1 to 4, wherein component (D) is a black or chromatic colorant. The resin composition layer according to any one of claims 1 to 5, wherein component (D) is a black or blue colorant. The resin composition layer according to any one of claims 1 to 6, wherein component (D) is a pigment. The resin composition layer according to any one of claims 1 to 7, wherein the amount of component (D) is 0.1% by mass or more and 5% by mass or less relative to 100% by mass of the non-volatile components in the resin composition. The resin composition layer according to any one of claims 1 to 8, wherein the amount of component (C) is 60 mass% or less relative to 100 mass% of the non-volatile components in the resin composition. The resin composition layer according to any one of claims 1 to 9, comprising at least one selected from the group consisting of bixylenol-type epoxy resins and fluorine-containing epoxy resins as component (A). The resin composition layer according to any one of claims 1 to 10 , for forming an insulating layer on which a conductor layer is to be formed. The resin composition layer according to any one of claims 1 to 11, which is used to form an interlayer insulating layer of a printed wiring board. The resin composition layer according to any one of claims 1 to 12, which is used to form an insulating layer having via holes with a top diameter of 35 μm or less. A support;
A resin sheet comprising: a layer of the resin composition according to any one of claims 1 to 13 provided on a support. A printed wiring board comprising an insulating layer formed from a cured product of a resin composition layer according to any one of claims 1 to 13. A semiconductor device including the printed wiring board according to claim 15.

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