JP7567969B2 - Photosensitive resin composition, photosensitive resin film, multilayer printed wiring board, semiconductor package, and method for manufacturing multilayer printed wiring board - Google Patents

Description

The present disclosure relates to a photosensitive resin composition, a photosensitive resin film, a multilayer printed wiring board, a semiconductor package, and a method for manufacturing a multilayer printed wiring board.

In recent years, with the trend toward smaller, lighter, more multifunctional electronic devices, multilayer printed wiring boards have become more dense due to an increase in the number of circuit layers and finer wiring. In particular, the density of semiconductor package substrates such as BGA (ball grid array) and CSP (chip size package) on which semiconductor chips are mounted has increased significantly, and in addition to finer wiring, there is a demand for thinner insulating films and smaller diameter vias (also called "via holes") for interlayer connection.

The most widely used method for manufacturing printed wiring boards is a build-up method (see, for example, Patent Document 1) in which an interlayer insulating layer and a conductor circuit layer are sequentially laminated to form a multilayer printed wiring board. As circuits become finer, the mainstream method for manufacturing multilayer printed wiring boards is a semi-additive method in which circuits are formed by plating.
In a conventional semi-additive method, for example, (1) a thermosetting resin film is laminated on a conductor circuit, and the thermosetting resin film is hardened by heating to form an "interlayer insulating layer", (2) next, vias for interlayer connection are formed by laser processing, and desmearing and roughening treatments are performed by alkaline permanganate treatment or the like, (3) thereafter, electroless copper plating is performed on the substrate, and after a pattern is formed using a resist, electrolytic copper plating is performed to form a copper circuit layer, and (4) next, the resist is peeled off, and the electroless layer is flash etched to form a copper circuit.

As mentioned above, conventionally, laser processing has been used as the main method for forming vias in an interlayer insulating layer formed by curing a thermosetting resin film. However, as via holes become smaller, the formation of via holes by laser irradiation using a laser processing machine is reaching its limit. Furthermore, when forming vias using a laser processing machine, each via hole must be formed one by one, and when a large number of vias are required to be provided due to high density, the formation of the vias takes a long time, resulting in poor manufacturing efficiency.

Under these circumstances, a method has been proposed that can form a large number of vias at once, which involves forming multiple small vias at once by photolithography using a photosensitive resin composition that contains (A) an acid-modified vinyl group-containing epoxy resin, (B) a photopolymerizable compound, (C) a photopolymerization initiator, (D) an inorganic filler, and (E) a silane compound, and in which the content of the inorganic filler (D) is 10 to 80 mass % (see, for example, Patent Document 2).

Japanese Patent Application Publication No. 7-304931 JP 2017-116652 A

The invention described in Patent Document 2 aims to suppress the decrease in adhesive strength with plated copper caused by using a photosensitive resin composition instead of a conventional thermosetting resin composition as a material for an interlayer insulating layer or a surface protective layer, and also aims to solve the problems of via resolution and adhesion with silicon substrates and chip components. However, as wiring becomes finer, insulating films become thinner, and via holes for interlayer connection become smaller in diameter, the required performance for via resolution and adhesive strength with plated copper becomes stricter, and there is room for further improvement in these performances.
It is also possible to use photosensitive resin compositions, which are conventional materials for solder resist, as materials for the interlayer insulating layer. However, since the interlayer insulating layer requires properties that are not necessary for solder resist, such as via resolution, adhesive strength with plated copper, interlayer insulating reliability, and high heat resistance capable of withstanding multiple heating processes, it is difficult to predict whether such a material will be practically usable as an interlayer insulating layer, and it is not possible to easily use such a material for the interlayer insulating layer.

The present invention has been made to solve the above problems, and aims to provide a photosensitive resin composition, a photosensitive resin composition for forming photovias, and a photosensitive resin composition for interlayer insulating layers, which are excellent in via resolution and adhesive strength with plated copper. It also aims to provide a photosensitive resin film and a photosensitive resin film for interlayer insulating layers made of the photosensitive resin composition, to provide a printed wiring board and a semiconductor package, and to provide a method for manufacturing the printed wiring board.

As a result of extensive research into solving the above problems, the inventors have discovered that the problems can be solved by the following invention. That is, the present invention provides the following photosensitive resin composition, photosensitive resin film, multilayer printed wiring board, semiconductor package, and method for producing a multilayer printed wiring board.

1. A photosensitive resin composition comprising (A) a photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton, (B) a photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton, and (C) a photopolymerization initiator.
2. The photosensitive resin composition according to 1 above, wherein (A) the photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton comprises (A1) a photopolymerizable compound having an acidic substituent together with an ethylenically unsaturated group and no isocyanuric skeleton.
3. The photosensitive resin composition according to the above 1 or 2, wherein the (B) photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton contains isocyanuric acid (meth)acrylate.
4. The photosensitive resin composition according to any one of 1 to 3 above, wherein the (B) photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton includes at least one selected from the group consisting of isocyanuric acid di(meth)acrylate and isocyanuric acid tri(meth)acrylate.
5. The photosensitive resin composition according to any one of 1 to 4 above, further comprising (D) a thermosetting resin.
6. The photosensitive resin composition according to any one of 1 to 5 above, further comprising (E) an elastomer.
7. The photosensitive resin composition according to any one of 1 to 6 above, further comprising (F) an inorganic filler.
8. The photosensitive resin composition according to any one of 1 to 7 above, wherein the content of the (A) photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton is 5 to 60 mass % based on the total solid content.
9. The photosensitive resin composition according to any one of 1 to 8 above, wherein the content of the (B) photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton is 0.5 to 15 mass % based on the total solid content.
10. The photosensitive resin composition according to any one of 1 to 9 above, wherein the content of the (C) photopolymerization initiator is 0.1 to 15 mass % based on the total solid content.
11. The photosensitive resin composition according to any one of 1 to 10 above, which is used for forming a photovia.
12. The photosensitive resin composition according to any one of 1 to 11 above, which is used for forming an interlayer insulating layer.
13. A photosensitive resin film comprising the photosensitive resin composition according to any one of 1 to 10 above.
14. The photosensitive resin film according to the above 13, which is used for forming an interlayer insulating layer.
15. A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin composition according to any one of 1 to 10 above.
16. A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin film according to 13 above.
17. A semiconductor package comprising the multilayer printed wiring board according to 15 or 16 above and a semiconductor element mounted thereon.
18. A method for producing a multilayer printed wiring board, comprising the steps of:
Step (1): A step of laminating the photosensitive resin film described in 13 above onto one or both sides of a circuit board.
Step (2): A step of forming an interlayer insulating layer having vias by exposing and developing the photosensitive resin film laminated in the step (1).
Step (3): A step of roughening the via and the interlayer insulating layer.
Step (4): forming a circuit pattern on the interlayer insulating layer.

According to the present invention, it is possible to provide a photosensitive resin composition having excellent via resolution and adhesive strength with plated copper, a photosensitive resin film made of the photosensitive resin composition, a multilayer printed wiring board using the photosensitive resin composition or the photosensitive resin film, and a semiconductor package using the multilayer printed wiring board.
It is also possible to provide a method for efficiently manufacturing a multilayer printed wiring board having smaller diameter, higher resolution vias and high adhesive strength between the interlayer insulating layer and the plated copper.

FIG. 2 is a schematic diagram showing one embodiment of a process for producing a multilayer printed wiring board using a cured product of the photosensitive resin composition of the present embodiment as at least one of a surface protective film and an interlayer insulating film.

The photosensitive resin composition according to one embodiment of the present invention (hereinafter, sometimes simply referred to as the present embodiment) is described in detail below.

[Photosensitive resin composition]
The photosensitive resin composition of the present embodiment comprises (A) a photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton, and (B) a photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton. and (C) a photopolymerization initiator.
In this specification, the above components may be referred to as component (A), component (B), component (C), etc., and the other components may be abbreviated in the same manner. The term "components" refers to the above-mentioned components (A), (B), and (C), and does not include the inorganic filler (F) described below. The term "solid content" refers to the photosensitive This refers to the non-volatile content of the resin composition excluding volatile substances such as water and solvents. It indicates the components that remain without volatilization when the resin composition is dried. It is also the value at room temperature around 25°C. This includes liquid, starch syrup and wax-like substances.
In this specification, the upper and lower limit values of a numerical range "to" can be arbitrarily combined, and the numerical values shown in the examples can be used as the upper and lower limit values. Furthermore, when a photosensitive resin composition contains a plurality of substances corresponding to each of the above components, the content of each of the components refers to the total content of the substances, unless otherwise specified.

The photosensitive resin composition of this embodiment is suitable for via formation by photolithography (also referred to as "photovia formation"), so the present invention also provides a photosensitive resin composition for photovia formation. In addition, the photosensitive resin composition is excellent in via resolution and adhesive strength with plated copper, and is suitable for forming an interlayer insulating layer of a multilayer printed wiring board, so the present invention also provides a photosensitive resin composition for an interlayer insulating layer. In this specification, the term "photosensitive resin composition" includes photosensitive resin compositions for photovia formation and photosensitive resin compositions for an interlayer insulating layer.
Each component that may be contained in the photosensitive resin composition of the present embodiment will be described in detail below.

<(A) Photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton>
The photosensitive resin composition of the present embodiment contains a photopolymerizable compound having an ethylenically unsaturated group as component (A) and having no isocyanuric skeleton. Examples of the ethylenically unsaturated group contained in component (A) include photopolymerizable functional groups such as vinyl group, allyl group, propargyl group, butenyl group, ethynyl group, phenylethynyl group, maleimide group, nadimide group, and (meth)acryloyl group. Among these photopolymerizable functional groups, the (meth)acryloyl group is preferred from the viewpoint of improving the resolution of vias and the adhesive strength with plated copper.
The component (A) is a compound that exhibits photopolymerizability due to the presence of an ethylenically unsaturated group, and is a component that imparts photopolymerizability to the photosensitive resin composition of the present embodiment. In addition, in the present embodiment, by using the component (A) in combination with a photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton, which will be described later, it is possible to obtain particularly excellent adhesive strength with plated copper.

From the viewpoint of improving the resolution of vias and the adhesive strength with plated copper, the photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton preferably includes at least one selected from (Ai) a monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group, (Aii) a bifunctional vinyl monomer having two polymerizable ethylenically unsaturated groups, and (Aiii) a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups, and more preferably includes the component (Aiii). The components (Ai) to (Aiii) preferably have a molecular weight of 1,000 or less.

((Ai) Monofunctional Vinyl Monomer)
Examples of the monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group include (meth)acrylic acid, (meth)acrylic acid alkyl esters, etc. Examples of the (meth)acrylic acid alkyl esters include (meth)acrylic acid methyl ester, (meth)acrylic acid ethyl ester, (meth)acrylic acid butyl ester, (meth)acrylic acid 2-ethylhexyl ester, (meth)acrylic acid hydroxyl ethyl ester, etc. The component (Ai) may be used alone or in combination of two or more kinds.

((Aii) Difunctional Vinyl Monomers)
Examples of the bifunctional vinyl monomer having two polymerizable ethylenically unsaturated groups include polyethylene glycol di(meth)acrylate, trimethylolpropane di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2-bis(4-(meth)acryloxypolyethoxypolypropoxyphenyl)propane, bisphenol A diglycidyl ether di(meth)acrylate, etc. The component (Aii) may be used alone or in combination of two or more types.

(Aiii) Multifunctional Vinyl Monomers
Examples of the polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups include (meth)acrylate compounds having a skeleton derived from trimethylolpropane, such as trimethylolpropane tri(meth)acrylate; (meth)acrylate compounds having a skeleton derived from tetramethylolmethane, such as tetramethylolmethane tri(meth)acrylate and tetramethylolmethane tetra(meth)acrylate; (meth)acrylate compounds having a skeleton derived from pentaerythritol, such as pentaerythritol tri(meth)acrylate and pentaerythritol tetra(meth)acrylate; (meth)acrylate compounds having a skeleton derived from dipentaerythritol, such as dipentaerythritol penta(meth)acrylate and dipentaerythritol hexa(meth)acrylate; (meth)acrylate compounds having a skeleton derived from ditrimethylolpropane, such as ditrimethylolpropane tetra(meth)acrylate; and (meth)acrylate compounds having a skeleton derived from diglycerin.
Among these, from the viewpoint of improving the resolution of vias and the adhesive strength with plated copper, a (meth)acrylate compound having a skeleton derived from dipentaerythritol is preferred, and dipentaerythritol penta(meth)acrylate is more preferred. The component (Aiii) may be used alone or in combination of two or more kinds.
Here, the "(meth)acrylate compound having a skeleton derived from..." (where "..." is the name of the compound) means an esterification product of the compound "..." and (meth)acrylic acid, and the esterification product also includes a compound modified with an alkyleneoxy group.

((A1) Photopolymerizable compound having an ethylenically unsaturated group and an acidic substituent and having no isocyanuric skeleton)
The photopolymerizable compound having an ethylenically unsaturated group is also preferably a photopolymerizable compound having an acidic substituent together with an ethylenically unsaturated group (A1) and not having an isocyanuric skeleton, from the viewpoint of enabling alkaline development and improving the resolution of vias and the adhesive strength with plated copper. Here, examples of the acidic substituent include a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, etc., and among them, a carboxyl group is preferred from the viewpoint of enabling alkaline development and improving the resolution of vias and the adhesive strength with plated copper.
As the component (A1), from the viewpoints of enabling alkaline development and improving the resolution of vias and the adhesive strength to plated copper, it is possible to use (A1-1) an acid-modified vinyl-group-containing epoxy resin derivative obtained by reacting (a1) an epoxy resin modified with (a2) a vinyl-group-containing organic acid (hereinafter sometimes referred to as "component (A')") with (a3) a saturated or unsaturated group-containing polybasic acid anhydride.

-(a1) Epoxy resin-
The (a1) epoxy resin is preferably an epoxy resin having two or more epoxy groups. Epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, etc. Among these, glycidyl ether type epoxy resins are preferred from the viewpoints of enabling alkaline development and improving via resolution and adhesive strength with plated copper.

Epoxy resins are also classified into various epoxy resins according to the difference in the main skeleton, and each of the above types of epoxy resins is further classified as follows: Specifically, bisphenol-based epoxy resins such as bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and bisphenol S-type epoxy resins; bisphenol-based novolac-type epoxy resins such as bisphenol A-type epoxy resins and bisphenol F-type novolac-type epoxy resins; novolac-type epoxy resins other than the above bisphenol-based novolac-type epoxy resins, such as phenol novolac-type epoxy resins, cresol novolac-type epoxy resins, and biphenyl novolac-type epoxy resins; phenol aralkyl-type epoxy resins; biphenyl aralkyl type epoxy resins; stilbene type epoxy resins; dicyclopentadiene type epoxy resins; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resins, naphthol novolac type epoxy resins, naphthol type epoxy resins, naphthol aralkyl type epoxy resins, and naphthylene ether type epoxy resins; biphenyl type epoxy resins; biphenyl aralkyl type epoxy resins; xylylene type epoxy resins; dihydroanthracene type epoxy resins; dicyclopentadiene type epoxy resins; alicyclic epoxy resins; aliphatic chain epoxy resins; and rubber-modified epoxy resins.
Among these, as the epoxy resin (a1), from the viewpoints of enabling alkaline development and improving the resolution of vias and the adhesive strength with plated copper, a bisphenol-based novolac type epoxy resin is preferred, and a bisphenol F novolac type epoxy resin is more preferred. The epoxy resin (a1) may be used alone or in combination of two or more kinds.

More specifically, the (a1) epoxy resin is preferably an epoxy resin having a structural unit represented by the following general formula (1).

In the general formula (1), R ¹¹ represents a hydrogen atom or a methyl group, and each Y ¹¹ independently represents a hydrogen atom or a glycidyl group. Each of the multiple R ¹¹ may be the same or different. At least one of the multiple Y ¹¹ represents a glycidyl group.
From the viewpoints of via resolution and adhesive strength with plated copper, it is preferable that each of R ¹¹ is a hydrogen atom, and from the same viewpoint, it is preferable that each of Y ¹¹ is a glycidyl group.
The number of structural units in the epoxy resin (a1) having the structural unit represented by general formula (1) is 1 or more, and is preferably 10 to 100, more preferably 15 to 80, and even more preferably 15 to 70. When the number of structural units is within the above range, adhesive strength, heat resistance, and insulating properties tend to be improved.
In general formula (1), those in which all R ¹¹ are hydrogen atoms and all Y ¹¹ are glycidyl groups are commercially available as the EXA-7376 series (trade name, manufactured by DIC Corporation), and those in which all R ¹¹ are methyl groups and all Y ¹¹ are glycidyl groups are commercially available as the EPON SU8 series (trade name, manufactured by Mitsubishi Chemical Corporation).

-(a2) Vinyl group-containing organic acid-
The vinyl group-containing organic acid (a2) is not particularly limited, but is preferably, for example, a vinyl group-containing monocarboxylic acid. Examples of the vinyl group-containing monocarboxylic acid include acrylic acid and acrylic acid derivatives. acrylic acid derivatives such as dimers, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, and α-cyanocinnamic acid; hydroxyl group-containing (meth)acrylates and dibasic acid anhydrides; a half-ester compound which is a reaction product of a vinyl group-containing monoglycidyl ether or a vinyl group-containing monoglycidyl ester with a dibasic acid anhydride; and the like.

The above-mentioned half-ester compound can be obtained, for example, by reacting a hydroxyl group-containing (meth)acrylate, a vinyl group-containing monoglycidyl ether, or a vinyl group-containing monoglycidyl ester with a dibasic acid anhydride in an equimolar ratio. The (a2) component may be used alone or in combination.

Examples of hydroxyl group-containing (meth)acrylates, vinyl group-containing monoglycidyl ethers, and vinyl group-containing monoglycidyl esters that can be used in the synthesis of the above-mentioned half-ester compounds given as examples of component (a2) include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, and glycidyl (meth)acrylate.

The dibasic acid anhydride used in the synthesis of the above-mentioned half ester compound may contain a saturated group or an unsaturated group. Examples of dibasic acid anhydrides include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride.

In the reaction between the above (a1) component and the above (a2) component, the reaction is preferably carried out in a ratio of 0.6 to 1.05 equivalents of the (a2) component per 1 equivalent of the epoxy group of the (a1) component, or may be carried out in a ratio of 0.8 to 1.0 equivalents. By carrying out the reaction in such a ratio, the photopolymerizability is improved, that is, the photosensitivity is increased, and the resolution of the vias tends to be improved.

The above-mentioned (a1) component and the above-mentioned (a2) component can be reacted in an organic solvent. Examples of the organic solvent include ketone-based organic solvents such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbon-based organic solvents such as toluene, xylene, and tetramethylbenzene; glycol ether-based organic solvents such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ester-based organic solvents such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate; aliphatic hydrocarbon-based organic solvents such as octane and decane; and petroleum-based organic solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha.

Furthermore, it is preferable to use a catalyst to promote the reaction between the above-mentioned (a1) component and the above-mentioned (a2) component. Examples of the catalyst include amine-based catalysts such as triethylamine and benzylmethylamine; quaternary ammonium salt catalysts such as methyltriethylammonium chloride, benzyltrimethylammonium chloride, benzyltrimethylammonium bromide and benzyltrimethylammonium iodide; and phosphine-based catalysts such as triphenylphosphine. Among them, phosphine-based catalysts are preferable, and triphenylphosphine is more preferable.
The amount of the catalyst used is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total of the components (a1) and (a2). This amount tends to promote the reaction between the components (a1) and (a2).

In order to prevent polymerization during the reaction, it is preferable to use a polymerization inhibitor, such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, etc.
When a polymerization inhibitor is used, the amount of the polymerization inhibitor used is, from the viewpoint of improving the storage stability of the photosensitive resin composition, preferably 0.01 to 1 part by mass, more preferably 0.02 to 0.8 parts by mass, and even more preferably 0.05 to 0.5 parts by mass, relative to 100 parts by mass in total of the component (a1) and the component (a2).

From the viewpoint of productivity, the reaction temperature between the above-mentioned (a1) component and the above-mentioned (a2) component is preferably 60 to 150°C, more preferably 80 to 120°C, and even more preferably 90 to 110°C.

The component (A') obtained by reacting the above-mentioned components (a1) and (a2) is presumed to have a hydroxyl group formed by a ring-opening addition reaction between the epoxy group of the component (a1) and the carboxyl group of the component (a2).

-(a3) Polybasic acid anhydride-
The (a3) component may contain a saturated group or an unsaturated group. Examples of the (a3) component include succinic anhydride, maleic anhydride, tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, and itaconic anhydride. Among these, tetrahydrophthalic anhydride is preferred from the viewpoint of via resolution.

By further reacting the above obtained component (A') with the saturated or unsaturated group-containing component (a3), it is presumed that the hydroxyl groups of component (A') (including the hydroxyl groups originally present in component (a1)) and the acid anhydride groups of component (a3) are semi-esterified to produce (A1-1) acid-modified vinyl group-containing epoxy resin derivative, which is a photopolymerizable compound that has an acidic substituent along with an ethylenically unsaturated group and does not have an isocyanuric skeleton.

In the reaction of the above component (A') with the above component (a3), for example, the acid value of the acid-modified vinyl group-containing epoxy resin derivative (A1-1) can be adjusted by reacting 0.1 to 1.0 equivalent of the component (a3) with respect to 1 equivalent of the hydroxyl group in the component (A').
The acid value of the acid-modified vinyl group-containing epoxy resin derivative (A1-1) is preferably 30 to 150 mgKOH/g, more preferably 40 to 120 mgKOH/g, and even more preferably 50 to 100 mgKOH/g. When the acid value is 30 mgKOH/g or more, the solubility of the photosensitive resin composition in a dilute alkaline solution is improved, and when it is 150 mgKOH/g or less, the electrical properties of the cured film tend to be improved.

From the viewpoint of productivity, the reaction temperature between the above component (A') and the above component (a3) is preferably 50 to 150°C, more preferably 60 to 120°C, and even more preferably 70 to 100°C.

As the acid-modified vinyl group-containing epoxy resin derivative (A1-1), commercially available products may be used. Examples of commercially available products include CCR-1218H, CCR-1159H, CCR-1222H, PCR-1050, TCR-1335H, ZAR-1035, ZAR-2001H, UXE-3024, ZFR-1185, ZCR-1569H, ZXR-1807, ZCR-6000, ZCR-8000 (all of which are product names manufactured by Nippon Kayaku Co., Ltd.), UE-9000, UE-EXP-2810PM, and UE-EXP-3045 (all of which are product names manufactured by DIC Corporation).

As the (A1) component, (A1-2) a styrene-maleic acid resin such as a hydroxyethyl (meth)acrylate modified styrene-maleic anhydride copolymer can also be used. In this case, the (A1-2) component can also be used in combination with the (A1-1) component. The (A1-2) component can be used alone or in combination of multiple types.

As the component (A1), an epoxy polyurethane resin (A1-3) obtained by reacting the compound obtained by modifying the epoxy resin (a1) with an organic acid containing a vinyl group (a2), i.e., the component (A'), with an isocyanate compound, can also be used. The component (A1-3) may be used alone or in combination with multiple types.

((A1) Molecular Weight of Photopolymerizable Compound Having an Ethylenically Unsaturated Group and an Acidic Substituent and No Isocyanuric Skeleton)
The weight average molecular weight (Mw) of component (A1) is preferably 3,000 to 30,000, more preferably 4,000 to 25,000, and even more preferably 5,000 to 18,000. Within this range, the resolution of vias and the adhesive strength to plated copper are improved. In particular, it is preferable that the weight average molecular weight (Mw) of the acid-modified vinyl group-containing epoxy resin derivative (A1-1) is within the above range. Here, in this specification, the weight average molecular weight is a value measured by the method described in the Examples.

(Content of component (A))
The content of component (A) is not particularly limited, but from the viewpoints of improving the resolution of vias and the adhesive strength with plated copper, as well as heat resistance, electrical properties, and chemical resistance, it is preferably 5 to 60 mass %, more preferably 10 to 55 mass %, even more preferably 20 to 50 mass %, and still more preferably 30 to 40 mass %, based on the total amount of resin components in the photosensitive resin composition.

The component (A) is not particularly limited, but from the viewpoint of improving the resolution of vias and the adhesive strength with plated copper, it is preferable to use the above component (A1) in combination with the above component (Aiii). In this case, the content ratio of the above component (A1) to the above component (Aiii) [(A1)/(Aiii)] (mass ratio) is preferably 2 to 20, more preferably 3 to 15, and even more preferably 4 to 12.

<(B) Photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton>
The photosensitive resin composition of the present embodiment contains a photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton as component (B). If component (B) is not contained, particularly excellent adhesive strength with plated copper cannot be obtained. The ethylenically unsaturated group of the photopolymerizable compound of component (B) may be the same as the functional group exhibiting photopolymerization listed as the ethylenically unsaturated group of component (A) above. Among them, from the viewpoint of improving the resolution of vias and the adhesive strength with plated copper, a (meth)acryloyl group is preferred, and an acryloyl group is more preferred.

(B) As the photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton, any compound having such an ethylenically unsaturated group and an isocyanuric skeleton can be used without any particular restrictions. For example, isocyanuric acid (meth)acrylate having a (meth)acryloyl group and an isocyanuric skeleton is preferred, isocyanuric acid di(meth)acrylate and isocyanuric acid tri(meth)acrylate are more preferred, and isocyanuric acid diacrylate and isocyanuric acid triacrylate are even more preferred.

Among these, alkylene oxide groups are introduced by alkylene oxide modification such as EO-modified isocyanuric acid di(meth)acrylate, EO-modified isocyanuric acid tri(meth)acrylate, PO-modified isocyanuric acid di(meth)acrylate, PO-modified isocyanuric acid tri(meth)acrylate, EO-PO-modified isocyanuric acid di(meth)acrylate, EO-PO-modified isocyanuric acid tri(meth)acrylate, and caprolactone-modified versions of these; and isocyanuric acid monoallyl type epoxy di(meth)acrylate, etc. are preferred. More specifically, for example, isocyanuric acid di(2-(meth)acryloyloxyethyl), isocyanuric acid tri(2-(meth)acryloyloxyethyl), alkylene oxide-modified versions of these, caprolactone-modified versions, etc. are preferred. These isocyanuric acid (meth)acrylates can be used alone or in combination.

(Content of component (B))
The content of the component (B) is not particularly limited, but from the viewpoint of improving the resolution of the vias and the adhesive strength with plated copper, it is preferably 0.1 to 20 mass %, more preferably 0.5 to 15 mass %, even more preferably 1 to 10 mass %, and still more preferably 3 to 8 mass %, based on the total amount of the resin components in the photosensitive resin composition.

<(C) Photopolymerization initiator>
The photosensitive resin composition of the present embodiment contains a photopolymerization initiator (C). If the photopolymerization initiator (C) is not contained, excellent via resolution and adhesive strength with plated copper cannot be obtained. The component (C) is not particularly limited as long as it can polymerize the component (A), and can be appropriately selected from commonly used photopolymerization initiators.

Examples of the photopolymerization initiator of the component (C) include benzoin-based photopolymerization initiators such as benzoin, benzoin methyl ether, and benzoin isopropyl ether; acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1,1-dichloroacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-methyl-1-[4-(methylthio) ) phenyl]-2-morpholino-1-propanone, N,N-dimethylaminoacetophenone, and other acetophenone-based photopolymerization initiators; 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2-aminoanthraquinone, and other anthraquinone-based photopolymerization initiators; 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, and other Thioxanthone-based photopolymerization initiators; ketal-based photopolymerization initiators such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenone-based photopolymerization initiators such as benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylamino)benzophenone, Michler's ketone and 4-benzoyl-4'-methyldiphenyl sulfide; acridine-based photopolymerization initiators such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; 2,4 , 6-trimethylbenzoyldiphenylphosphine oxide and other acylphosphine oxide-based photopolymerization initiators; and oxime ester-based photopolymerization initiators such as 1,2-octanedione-1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetyloxime), 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl)oxime] and other. Among these, acetophenone-based photopolymerization initiators and thioxanthone-based photopolymerization initiators are preferred, with 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone and 2,4-diethylthioxanthone being more preferred.
The component (C) may be used alone or in combination of two or more types. When using two or more types in combination, it is preferable to use an acetophenone-based photopolymerization initiator in combination with a thioxanthone-based photopolymerization initiator, and it is more preferable to use 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone in combination with 2,4-diethylthioxanthone.

(Content of component (C))
The content of component (C) is not particularly limited, but is preferably 0.1 to 15 mass%, more preferably 0.2 to 5 mass%, and even more preferably 0.4 to 1.5 mass%, based on the total amount of resin components in the photosensitive resin composition. If the content of component (C) is 0.1 mass% or more, the risk of the exposed portion of the interlayer insulating layer formed using the photosensitive resin composition being eluted during development is reduced, and if it is 15 mass% or less, heat resistance tends to be improved.

<(C') Photopolymerization Initiator Auxiliary Agent>
The photosensitive resin composition of the present embodiment may contain a photopolymerization initiation aid (C') together with the component (C). Examples of the photopolymerization initiation aid (C') include tertiary amine-based photopolymerization initiation aids such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, and triethanolamine. The component (C') may be used alone or in combination of two or more kinds.
When the photosensitive resin composition of the present embodiment contains the component (C'), the content thereof is preferably 0.01 to 1 mass %, more preferably 0.03 to 0.5 mass %, and even more preferably 0.05 to 0.3 mass %, based on the total amount of the resin components of the photosensitive resin composition. Note that the photosensitive resin composition of the present embodiment does not necessarily contain the component (C').

<(D) Thermosetting resin>
The photosensitive resin composition of the present embodiment may further contain a thermosetting resin (D) in addition to the above-mentioned components (A) to (C). In addition to improving the via resolution and adhesive strength with plated copper, heat resistance is also improved.
Examples of the thermosetting resin include epoxy resin, phenol resin, unsaturated imide resin, cyanate resin, isocyanate resin, benzoxazine resin, oxetane resin, amino resin, unsaturated polyester resin, allyl resin, dicyclopentadiene resin, and silicone. Resins, triazine resins, melamine resins, etc. are included. In addition, there is no particular limitation to these, and known thermosetting resins can be used. These thermosetting resins can be used alone or in combination of two or more kinds. It is possible.
Among them, epoxy resins are preferred. The epoxy resin does not include any resin that corresponds to the component (A), and in this respect, the epoxy resin used as the thermosetting resin (D) does not have an ethylenically unsaturated group. In addition, substances that satisfy the above conditions and have an epoxy group are included in component (D).

The epoxy resin of component (D) is preferably an epoxy resin having two or more epoxy groups. Epoxy resins are classified into glycidyl ether type epoxy resins, glycidyl amine type epoxy resins, glycidyl ester type epoxy resins, etc. Among these, glycidyl ether type epoxy resins are preferred.

Epoxy resins are also classified into various epoxy resins according to the difference in the main skeleton, and each of the above types of epoxy resins is further classified as follows. Specifically, bisphenol-based epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; bisphenol-based novolac type epoxy resins such as bisphenol A novolac type epoxy resin and bisphenol F novolac type epoxy resin; novolac type epoxy resins other than the above bisphenol-based novolac type epoxy resins, such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, and biphenyl novolac type epoxy resin; phenol aralkyl type epoxy resin; biphenyl aralkyl type epoxy resin; stilbene type epoxy resin; dicyclopentadiene type epoxy resin; type epoxy resins; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resins, naphthol novolac type epoxy resins, naphthol type epoxy resins, naphthol aralkyl type epoxy resins, and naphthylene ether type epoxy resins; biphenyl type epoxy resins; biphenyl aralkyl type epoxy resins; xylylene type epoxy resins; dihydroanthracene type epoxy resins; dicyclopentadiene type epoxy resins; alicyclic epoxy resins; heterocyclic epoxy resins; spiro ring-containing epoxy resins; cyclohexane dimethanol type epoxy resins; trimethylol type epoxy resins; aliphatic linear epoxy resins; rubber-modified epoxy resins; and others.

Among these, from the viewpoint of improving the adhesive strength with plated copper and further improving heat resistance, bisphenol-based epoxy resins, naphthol-type epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, and naphthylene ether-type epoxy resins are preferred, bisphenol A-type epoxy resins, bisphenol F-type epoxy resins, and biphenyl-type epoxy resins are more preferred, bisphenol F-type epoxy resins and biphenyl-type epoxy resins are even more preferred, and biphenyl-type epoxy resins are even more preferred.

These epoxy resins may be commercially available products, such as bisphenol A type epoxy resins (Mitsubishi Chemical Corporation's "Epicoat 828EL" and "YL980"), bisphenol F type epoxy resins (Mitsubishi Chemical Corporation's "jER806H" and "YL983U"), naphthalene type epoxy resins (DIC Corporation's "HP4032D" and "HP4710"), naphthalene skeleton-containing multifunctional epoxy resins (Nippon Kayaku Co., Ltd.'s "NC7000"), naphthol type epoxy resins (Nippon Steel & Sumitomo Metals Co., Ltd.'s "Nippon Steel & Sumitomo Metals Co., Ltd."), and the like. Examples of epoxy resins include epoxy resins having a biphenyl structure ("NC3000H" and "NC3500" manufactured by Nippon Kayaku Co., Ltd.), epoxy resins having a biphenyl structure ("YX4000", "YX4000HK", and "YL6121" manufactured by Mitsubishi Chemical Corporation), anthracene-type epoxy resins ("YX8800" manufactured by Mitsubishi Chemical Corporation), glycerol-type epoxy resins ("ZX1542" manufactured by Nippon Steel & Sumitomo Metal Corporation), and naphthylene ether-type epoxy resins ("EXA7311-G4" manufactured by DIC Corporation).

As the epoxy resin of the thermosetting resin (D), in addition to the resins exemplified above, epoxy-modified polybutadiene can be used. As the epoxy resin of the component (D), it is preferable to use an aromatic epoxy resin that is solid at room temperature in combination with an epoxy resin that is liquid at room temperature. From this viewpoint, it is preferable to use the epoxy resin exemplified as a preferred one (aromatic epoxy resin that is solid at room temperature) in combination with epoxy-modified polybutadiene (epoxy resin that is liquid at room temperature). In this case, the content ratio of the two used in combination (aromatic epoxy resin that is solid at room temperature/epoxy resin that is liquid at room temperature) is preferably 100/5 to 60/40, more preferably 90/10 to 70/30, by mass ratio.

The epoxy-modified polybutadiene preferably has hydroxyl groups at the molecular terminals, more preferably has hydroxyl groups at both molecular terminals, and even more preferably has hydroxyl groups only at both molecular terminals. The number of hydroxyl groups possessed by the epoxy-modified polybutadiene is not particularly limited as long as it is one or more, but is preferably 1 to 5, more preferably 1 or 2, and even more preferably 2.
From the viewpoints of adhesive strength with plated copper, heat resistance, thermal expansion coefficient and flexibility, the epoxy-modified polybutadiene is preferably an epoxy-modified polybutadiene represented by the following general formula (2):

(In the above general formula (2), n ₂₁ , n ₂₂ and n ₂₃ each represent a ratio of the structural unit in parentheses, n ₂₁ is 0.05 to 0.40, n ₂₂ is 0.02 to 0.30, n ₂₃ is 0.30 to 0.80, and further, n ₂₁ + n ₂₂ + n ₂₃ = 1.00 and (n ₂₁ + n ₂₃ ) > n ₂₂ are satisfied. _{y 21} represents the number of structural units in square brackets and is an integer of 10 to 250.)

The structural units in the general formula (2) may be bonded in any order. In other words, the structural unit shown on the left, the structural unit shown in the center, and the structural unit shown on the right may be interchanged, and when represented as (a), (b), and (c), respectively, various bonding orders are possible, such as -[(a)-(b)-(c)]-[(a)-(b)-(c)-]-, -[(a)-(c)-(b)]-[(a)-(c)-(b)-]-, -[(b)-(a)-(c)]-[(b)-(a)-(c)-]-, -[(a)-(b)-(c)]-[(c)-(b)-(a)-]-, -[(a)-(b)-(a)]-[(c)-(b)-(c)-]-, -[(a)-(b)-(a)]-[(c)-(b)-(c)-]-, -[(c)-(b)-(c)]-[(b)-(a)-(a)-]-.
From the viewpoint of improving the adhesive strength with plated copper as well as heat resistance, thermal expansion coefficient, and flexibility, _n21 is preferably 0.10 to 0.30, _n22 is preferably 0.10 to 0.30, and _n23 is preferably 0.40 to 0.80. From the same viewpoint, _y21 is preferably an integer of 5 to 500.

In the general formula (2), examples of commercially available epoxidized polybutadiene in which n ₂₁ =0.20, n ₂₂ =0.20, n ₂₃ =0.60, and y ₂₁ =an integer of 10 to 250 include "Epolead (registered trademark) PB3600" (manufactured by Daicel Corporation).

(Content of component (D))
The content of component (D) is not particularly limited, but is preferably 5 to 70 mass %, more preferably 5 to 40 mass %, even more preferably 7 to 30 mass %, and particularly preferably 10 to 20 mass %, based on the total amount of resin components in the photosensitive resin composition. When the content of component (D) is 5 mass % or more, sufficient crosslinking of the photosensitive resin composition is obtained, and the adhesive strength with plated copper is improved, while when it is 70 mass % or less, the resolution of vias tends to be good.

<(E) Elastomer>
The photosensitive resin composition of this embodiment may further contain an elastomer (E) in addition to the above components (A) to (C). By containing the elastomer (E), the resolution of the vias and the adhesive strength with the plated copper are improved. In addition, the component (E) has the effect of suppressing the decrease in flexibility and adhesive strength with the plated copper caused by the distortion (internal stress) inside the cured product due to the cure shrinkage of the component (A).

Examples of the elastomer include styrene-based elastomers, olefin-based elastomers, polyester-based elastomers, urethane-based elastomers, polyamide-based elastomers, acrylic-based elastomers, silicone-based elastomers, etc., and it is preferable to use at least one selected from these. These elastomers are composed of a hard segment component and a soft segment component, and the former tends to contribute to heat resistance and strength, while the latter tends to contribute to flexibility and toughness.
Among the elastomers exemplified above, from the viewpoints of improving the adhesive strength with plated copper and further improving compatibility and solubility with the resin component, it is preferable that component (E) contains at least one selected from olefin-based elastomers, polyester-based elastomers, and urethane-based elastomers, and it is more preferable that component (E) contains a urethane-based elastomer. It is further preferable that component (E) is at least one selected from olefin-based elastomers, polyester-based elastomers, and urethane-based elastomers, and it is particularly preferable that component (E) is a urethane-based elastomer.

(styrene elastomer)
Examples of the styrene-based elastomer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, and styrene-ethylene-propylene-styrene block copolymer.

As the styrene-based elastomer, commercially available products may be used, such as Tufprene, Solprene T, Asaprene T, and Tuftec (all manufactured by Asahi Kasei Corporation; "Tufprene", "Asaprene" and "Tuftec" are registered trademarks), Elastomer AR (manufactured by Aronkasei Co., Ltd.), Kraton G, Kakariflex (all manufactured by Shell Japan Co., Ltd.), JSR-TR, TSR-SIS, and Dynaron (all manufactured by JSR Corporation), Denka STR (manufactured by Denka Co., Ltd.), and Qui Examples include Quintac (manufactured by Zeon Corporation, "Quintac" is a registered trademark), TPE-SB series (manufactured by Sumitomo Chemical Co., Ltd.), Rabalon (manufactured by Mitsubishi Chemical Corporation, "Rabalon" is a registered trademark), Septon, Hybra (all manufactured by Kuraray Co., Ltd., "Septon" and "Hybra" are registered trademarks), Sumiflex (manufactured by Sumitomo Bakelite Co., Ltd.), Leostomer, and Actimer (all manufactured by RIKEN TECHNOS Corporation, "Leostomer" and "Actimer" are registered trademarks).

(Olefin elastomer)
Examples of olefin elastomers include polymers or copolymers of α-olefins having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, and 4-methyl-pentene. The olefin elastomer may have a hydroxyl group at the molecular end, and preferably has a hydroxyl group at the molecular end.
Examples of olefin elastomers include polyethylene, polybutadiene, hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisopropylene, ethylene-propylene copolymer (EPR), ethylene-propylene-diene copolymer (EPDM), etc. Also included are copolymers of the above-mentioned α-olefins having 2 to 20 carbon atoms with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, isoprene, etc. Still other examples include carboxy-modified NBR obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid.
The olefin elastomer preferably has a number average molecular weight of 1,000 to 5,000, more preferably 1,500 to 3,500.

As the olefin-based elastomer, commercially available products may be used, and examples of commercially available products include Mirastoma (manufactured by Mitsui Chemicals, Inc., product name), EXACT (manufactured by Exxon Mobil Corporation, product name), ENGAGE (manufactured by The Dow Chemical Company, product name), Poly ip, Poly bd (Idemitsu Kosan Co., Ltd., product name), hydrogenated styrene-butadiene rubber "DYNABON HSBR" (manufactured by JSR Corporation, product name), butadiene-acrylonitrile copolymer "NBR series" (manufactured by JSR Corporation, product name), butadiene-acrylonitrile copolymer "XER series" (manufactured by JSR Corporation, product name) modified with carboxyl groups at both ends, epoxidized polybutadiene BF-1000 (manufactured by Nippon Soda Co., Ltd., product name), PB-4700, PB-3600 (manufactured by Daicel Corporation, product names), etc.

(Polyester elastomer)
Examples of polyester-based elastomers include those obtained by polycondensation of dicarboxylic acid or a derivative thereof and a diol compound or a derivative thereof.
Specific examples of the dicarboxylic acid include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; aromatic dicarboxylic acids in which hydrogen atoms on the aromatic ring of the aromatic dicarboxylic acid are substituted with methyl, ethyl, or phenyl groups; aliphatic dicarboxylic acids having 2 to 20 carbon atoms such as adipic acid, sebacic acid, and dodecanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid. As the dicarboxylic acid, it is also preferable to use a dimer acid derived from a natural product from the viewpoint of improving the resolution of vias, the adhesive strength with plated copper, and the insulation reliability. The dicarboxylic acid may be used alone or in combination of two or more kinds.
Specific examples of the diol compound include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and 1,10-decanediol; alicyclic diols such as 1,4-cyclohexanediol; etc. The diol compounds may be used alone or in combination.
The polyester elastomer preferably has a number average molecular weight of 900 to 30,000, more preferably 1,000 to 25,000, and even more preferably 5,000 to 15,000.

As the polyester-based elastomer, commercially available products may be used, such as Hytrel (manufactured by DuPont-Toray Co., Ltd., "Hytrel" is a registered trademark), Pelprene (manufactured by Toyobo Co., Ltd., "Pelprene" is a registered trademark), and Espel (manufactured by Hitachi Chemical Co., Ltd., "Espel" is a registered trademark).

(Urethane elastomer)
Examples of urethane-based elastomers include those containing a hard segment made of a short-chain diol and a diisocyanate, and a soft segment made of a polymeric (long-chain) diol and a diisocyanate.
Examples of the polymeric (long-chain) diol include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), poly(1,6-hexylene-neopentylene adipate), etc. The number average molecular weight of the polymeric (long-chain) diol is preferably 500 to 10,000.
Examples of the short-chain diol include ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A. The number average molecular weight of the short-chain diol is preferably 48 to 500.

As the urethane-based elastomer, commercially available products may be used, such as PANDEX T-2185 and T-2983N (both manufactured by DIC Corporation), the Miractoran series (manufactured by Nippon Miractoran Co., Ltd., "Miractran" is a registered trademark), and the Hitaloid series (manufactured by Hitachi Chemical Co., Ltd., "Hitaroid" is a registered trademark), etc.

(Polyamide elastomer)
Examples of polyamide-based elastomers include block copolymers having polyamide as a hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, silicone rubber, or the like as a soft segment component.

As the polyamide-based elastomer, commercially available products may be used, such as UBE polyamide elastomer (manufactured by Ube Industries, Ltd.), DAIAMID (manufactured by Daicel-Evonik Ltd., "DAIAMID" is a registered trademark), PEBAX (manufactured by Toray Industries, Inc.), GRILLON ELY (manufactured by M-Chemie Japan, "GRILLON" is a registered trademark), NOVAMID (manufactured by Mitsubishi Chemical Corporation), and GLYX (manufactured by Toyobo Co., Ltd., "GLYX" is a registered trademark).

(Acrylic elastomer)
Examples of acrylic elastomers include polymers of raw material monomers mainly composed of acrylic acid esters. Suitable examples of acrylic acid esters include ethyl acrylate, butyl acrylate, methoxyethyl acrylate, and ethoxyethyl acrylate. The crosslinking point monomer may be a copolymer of glycidyl methacrylate, allyl glycidyl ether, or acrylonitrile, ethylene, or the like. Specific examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer.

(Silicone elastomer)
Silicone-based elastomers are elastomers whose main component is organopolysiloxane, and are classified into, for example, polydimethylsiloxane-based elastomers, polymethylphenylsiloxane-based elastomers, polydiphenylsiloxane-based elastomers, and the like.

Commercially available silicone elastomers may be used, such as the KE series (manufactured by Shin-Etsu Chemical Co., Ltd.), SE series, CY series, and SH series (all manufactured by Dow Corning Toray Co., Ltd.).

(Other elastomers)
Also preferred is an embodiment in which the component (E) includes at least one selected from the group consisting of polyphenylene ether resin, phenoxy resin, polycarbonate resin, polyamideimide resin, polyimide resin, xylene resin, polyphenylene sulfide resin, polyetherimide resin, polyetheretherketone resin, polyetherimide resin, tetrafluoroethylene resin, polyacrylonitrile resin, maleic anhydride-modified polybutadiene, phenol-modified polybutadiene, and carboxy-modified polyacrylonitrile.

(Content of component (E))
The content of component (E) in the photosensitive resin composition of this embodiment is preferably 2 to 30 mass% based on the total amount of resin components in the photosensitive resin composition, more preferably 2 to 20 mass%, even more preferably 3 to 15 mass%, still more preferably 3 to 10 mass%, and particularly preferably 5 to 10 mass%. When the content of component (E) is 2 mass% or more, the adhesive strength with plated copper is improved, and when it is 30 mass% or less, the resolution of the via and the adhesive strength with plated copper tend to be improved.

<(F) Inorganic Filler>
The photosensitive resin composition of this embodiment may contain an inorganic filler (F). By containing the inorganic filler (F), the resolution of the vias is improved, and the low thermal expansion is improved, so that the occurrence of warping can be further reduced. In the thermosetting resin composition that has been conventionally used as an interlayer insulating layer of a multilayer printed wiring board, the low thermal expansion has been achieved by containing an inorganic filler, but when an inorganic filler is contained in a photosensitive resin composition, the inorganic filler causes light scattering and becomes an obstacle to development, so it was difficult to contain a large amount of inorganic filler to achieve low thermal expansion. Thus, there is a new problem unique to the photosensitive resin composition in containing an inorganic filler, but the photosensitive resin composition of this embodiment has high via resolution even if a large amount of inorganic filler is contained. As a result, in this embodiment, by using the inorganic filler (F), it has become possible to achieve high via resolution and low thermal expansion.

Examples of the (F) component include silica (SiO ₂ ), alumina (Al ₂ O ₃ ), titania (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), zirconia (ZrO ₂ ), silicon nitride (Si ₃ N ₄ ), barium titanate (BaO.TiO ₂ ), barium carbonate (BaCO ₃ ), magnesium carbonate (MgCO ₃ ), aluminum hydroxide (Al(OH) ₃ ), magnesium hydroxide (Mg(OH) ₂ ), lead titanate (PbO.TiO ₂ ), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), gallium oxide (Ga ₂ O ₃ ), spinel (MgO.Al ₂ O ₃ ), mullite (3Al ₂ O 3.2SiO ₂ ), cordierite (2MgO.2Al _{2 O} 3 ), and the _like . ₃ / _5SiO2 ), talc ( _{3MgO.4SiO2.H2O} ) _, aluminum titanate (TiO2.Al2O3), _{yttria -} containing zirconia ( _Y2O3.ZrO2 ), barium silicate ( _BaO.8SiO2 ), boron nitride (BN ₎ , calcium carbonate ( _CaCO3 ), barium sulfate ( _BaSO4 ), calcium _sulfate ( _CaSO4 ) _, zinc oxide (ZnO), magnesium titanate ( _MgO.TiO2 ), hydrotalcite, mica, calcined kaolin, carbon (C), etc. Component (F) can be used alone or in combination of two or more kinds.

From the viewpoint of via resolution, the average particle size of the inorganic filler (F) is preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm, and even more preferably 0.1 to 2 μm. In this specification, the average particle size of the inorganic filler (B) is the average particle size of the inorganic filler in a state dispersed in the photosensitive resin composition, and is a value obtained by measuring as follows.
First, the photosensitive resin composition is diluted (or dissolved) 1,000 times with methyl ethyl ketone, and then the particles dispersed in the solvent are measured with a submicron particle analyzer (manufactured by Beckman Coulter, Inc., product name: N5) in accordance with the international standard ISO 13321 at a refractive index of 1.38, and the particle diameter at an integrated value of 50% (volume basis) in the particle size distribution is taken as the volume average particle diameter, which is taken as the average particle diameter of the inorganic filler. In addition, the (F) component contained in the photosensitive resin film and interlayer insulating layer provided on the carrier film can also be measured by diluting (or dissolving) 1,000 times (volume ratio) with a solvent as described above, and then using the submicron particle analyzer.

(Content of component (F))
The content of the component (F) is not particularly limited, but from the viewpoint of improving the resolution of the vias, the adhesive strength to plated copper, and the insulation reliability, it is preferably 5 to 80 mass %, more preferably 15 to 60 mass %, and even more preferably 25 to 55 mass %, based on the total solid content of the photosensitive resin composition.

<(G) Thermal Polymerization Initiator>
The photosensitive resin composition of the present embodiment may further contain a thermal polymerization initiator (G) in addition to the above components (A) to (C). By containing the thermal polymerization initiator (G), the resolution of the via and the adhesive strength with plated copper are improved.
The thermal polymerization initiator is not particularly limited, and examples thereof include hydroperoxide-based thermal polymerization initiators such as diisopropylbenzene hydroperoxide "Percumyl P" (trade name, manufactured by NOF Corporation (hereinafter the same)), cumene hydroperoxide "Percumyl H", and t-butyl hydroperoxide "Perbutyl H"; α,α-bis(t-butylperoxy-m-isopropyl)benzene "Perbutyl P", dicumyl peroxide "Percumyl D", 2,5-dimethyl-2,5-bis(t-butylperoxy)hexane "Perhexa 25B", t-butylcumyl peroxide "Perbutyl C", di-t-butyl peroxide "Perbutyl ...butyl H", and the like. Examples of the thermal polymerization initiator include dialkyl peroxidase-based thermal polymerization initiators such as (t-butylperoxy)hexyne-3 "Perhexyne 25B" and t-butylperoxy-2-ethylhexanoate "Perbutyl O"; ketone peroxide-based thermal polymerization initiators; peroxyketal-based thermal polymerization initiators such as n-butyl 4,4-di-(t-butylperoxy)valerate "Perhexa V"; diacyl peroxide-based thermal polymerization initiators; peroxydicarbonate-based thermal polymerization initiators; and organic peroxides such as peroxyester-based thermal polymerization initiators; azo compounds such as 2,2'-azobisisobutylnitrile, 2,2'-azobis(2-cyclopropylpropionitrile), and 2,2'-azobis(2,4-dimethylvaleronitrile). Among these, from the viewpoint of not inhibiting photopolymerization and being highly effective in improving the physical properties and characteristics of the photosensitive resin composition, dialkyl peroxoside-based thermal polymerization initiators are preferred, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne-3 is more preferred.
The thermal polymerization initiators may be used alone or in combination of two or more kinds.

(Content of component (G))
When the photosensitive resin composition of the present embodiment contains the component (G), its content is not particularly limited, but from the viewpoint of improving the resolution of the via and the adhesive strength with plated copper, it is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, and even more preferably 0.1 to 1 mass %, based on the total amount of the resin components in the photosensitive resin composition.

<(H) Pigment>
The photosensitive resin composition of the present embodiment may contain a pigment as component (H) according to the desired color in order to adjust the photosensitivity and improve the appearance by hiding the conductor pattern, etc. As component (H), a colorant that develops the desired color may be appropriately selected and used, and preferred examples thereof include known colorants such as phthalocyanine blue, phthalocyanine green, iodine green, diazo yellow, crystal violet, titanium oxide, carbon black, and naphthalene black.

(Content of component (H))
When the photosensitive resin composition of the present embodiment contains the component (H), the content thereof is preferably 0.01 to 5 mass %, more preferably 0.03 to 3 mass %, and even more preferably 0.05 to 2 mass %, based on the total solid content of the photosensitive resin composition, from the viewpoints of making the production equipment easier to identify and further concealing the conductor pattern.

<(I) Epoxy Resin Curing Agent>
The photosensitive resin composition of the present embodiment may further contain (I) an epoxy resin curing agent for the purpose of further improving various properties of the resulting insulating layer, such as heat resistance, adhesion, and chemical resistance.
Specific examples of the component (I) include imidazole derivative-based epoxy resin curing agents such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole; guanamine-based epoxy resin curing agents such as acetoguanamine and benzoguanamine; diaminodiphenylmethane, m-phenylenediamine, m-xylylenediamine, diaminodiphenylsulfone, and dicyandiamine. Polyamine-based epoxy resin curing agents such as amides, urea, urea derivatives, melamine, and polybasic hydrazides; organic acid salts and/or epoxy adducts thereof; amine complexes of boron trifluoride; triazine derivative-based epoxy resin curing agents such as ethyldiamino-S-triazine, 2,4-diamino-S-triazine, and 2,4-diamino-6-xylyl-S-triazine; trimethylamine, N,N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmorpholine, and hexa(N-methyl)amine. tertiary amine-based epoxy resin curing agents such as melamine, 2,4,6-tris(dimethylaminophenol), tetramethylguanidine, and m-aminophenol; polyphenol-based epoxy resin curing agents such as polyvinylphenol, polyvinylphenol bromide, phenol novolac, and alkylphenol novolac; organic phosphine-based epoxy resin curing agents such as tributylphosphine, triphenylphosphine, and tris-2-cyanoethylphosphine; phosphonium salt-based epoxy resin curing agents such as tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributylphosphonium chloride; quaternary ammonium salt-based epoxy resin curing agents such as benzyltrimethylammonium chloride and phenyltributylammonium chloride; the above-mentioned polybasic acid anhydrides; diphenyliodonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, and 2,4,6-triphenylthiopyrylium hexafluorophosphate.

(Content of component (I))
When the photosensitive resin composition of the present embodiment contains the component (I), the content thereof is preferably 0.01 to 20 mass %, more preferably 0.1 to 10 mass %, and even more preferably 0.5 to 2 mass %, based on the total amount of the resin components in the photosensitive resin composition.

<Diluent>
A diluent can be used in the photosensitive resin composition of the present embodiment as necessary. As the diluent, for example, an organic solvent can be used. As the organic solvent, for example, ketone-based organic solvents such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbon-based organic solvents such as toluene, xylene, and tetramethylbenzene; glycol ether-based organic solvents such as methyl cellosolve, butyl cellosolve, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, and triethylene glycol monoethyl ether; ester-based organic solvents such as ethyl acetate, butyl acetate, propylene glycol monoethyl ether acetate, butyl cellosolve acetate, and carbitol acetate; aliphatic hydrocarbon-based organic solvents such as octane and decane; petroleum-based organic solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The diluent may be used alone or in combination.

(Diluent Content)
The content of the diluent may be appropriately selected so that the concentration of the total solid content in the photosensitive resin composition is preferably 50 to 90 mass%, more preferably 60 to 80 mass%, and even more preferably 65 to 75 mass%. By adjusting the amount of the diluent used in this manner, the coatability of the photosensitive resin composition is improved, and it becomes possible to easily form a higher-definition pattern.

<Other additives>
The photosensitive resin composition of the present embodiment may contain various known and commonly used additives, such as polymerization inhibitors such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, and pyrogallol, thickeners such as bentone and montmorillonite, antifoaming agents such as silicone-based antifoaming agents, fluorine-based antifoaming agents, and vinyl resin-based antifoaming agents, and silane coupling agents, as required.Furthermore, flame retardants such as brominated epoxy compounds, acid-modified brominated epoxy compounds, phosphate compounds of antimony compounds and phosphorus-based compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters may be contained.

The photosensitive resin composition of the present embodiment can be obtained by kneading and mixing the components using a roll mill, a bead mill, or the like.
Here, the photosensitive resin composition of the present embodiment may be used in the form of a liquid or a film.
When used in a liquid form, the method for applying the photosensitive resin composition of the present embodiment is not particularly limited, and examples thereof include various application methods such as printing, spin coating, spray coating, jet dispensing, inkjet, dip coating, etc. Among these, from the viewpoint of more easily forming the photosensitive layer, the printing method or spin coating method may be appropriately selected.
When used in the form of a film, it can be used in the form of a photosensitive resin film described later, for example, and in this case, a photosensitive layer of a desired thickness can be formed by laminating it on a carrier film using a laminator, etc. Note that using it in the form of a film is preferable because it increases the production efficiency of multilayer printed wiring boards.

[Photosensitive resin film]
The photosensitive resin film of the present embodiment is made of the photosensitive resin composition of the present embodiment and is preferably used for forming a photosensitive layer that becomes an interlayer insulating layer, for example. The photosensitive resin film of the embodiment may be in a form in which the photosensitive resin film is provided on a carrier film.
The thickness (thickness after drying) of the photosensitive resin film (photosensitive layer) is not particularly limited, but from the viewpoint of thinning the multilayer printed wiring board, it is preferably 1 to 100 μm, more preferably 1 to 50 μm, and even more preferably 5 to 40 μm.

The photosensitive resin film of the present embodiment can be obtained, for example, by applying the photosensitive resin composition of the present embodiment onto a carrier film using a known coating device such as a comma coater, a bar coater, a kiss coater, a roll coater, a gravure coater, or a die coater, and drying the composition to form a photosensitive layer that will later become an interlayer insulating layer.
Examples of the carrier film include polyesters such as polyethylene terephthalate and polybutylene terephthalate, polyolefins such as polypropylene and polyethylene, etc. The thickness of the carrier film may be appropriately selected from the range of 5 to 100 μm, preferably 5 to 60 μm, more preferably 15 to 45 μm.

The photosensitive resin film of this embodiment may also have a protective film on the surface of the photosensitive layer opposite the surface in contact with the carrier film. The protective film may be, for example, a polymer film such as polyethylene or polypropylene. The same polymer film as the carrier film described above may be used, or a different polymer film may be used.

The coating film formed by applying the photosensitive resin composition can be dried using hot air drying, a dryer using far infrared rays, or a dryer using near infrared rays. The drying temperature is preferably 60 to 150°C, more preferably 70 to 120°C, and even more preferably 80 to 100°C. The drying time is preferably 1 to 60 minutes, more preferably 2 to 30 minutes, and even more preferably 5 to 20 minutes. The content of the remaining diluent in the photosensitive resin film after drying is preferably 3% by mass or less, more preferably 2% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of avoiding diffusion of the diluent during the manufacturing process of the multilayer printed wiring board.

The photosensitive resin film of this embodiment is suitable as an interlayer insulating layer for a multilayer printed wiring board because it has excellent via resolution, adhesive strength with plated copper, and insulation reliability. In other words, the photosensitive resin film of this embodiment is suitable as a photosensitive resin film for an interlayer insulating layer that is preferably used for forming an interlayer insulating layer. Note that a photosensitive resin film for an interlayer insulating layer is also generally referred to as an interlayer insulating film.

[Multilayer printed wiring board and its manufacturing method]
The multilayer printed wiring board of the present embodiment includes an interlayer insulating layer formed using the photosensitive resin composition of the present embodiment (photosensitive resin film for interlayer insulating layer). The multilayer printed wiring board of the present embodiment is not particularly limited in its manufacturing method as long as it includes a step of forming an interlayer insulating layer using the photosensitive resin composition of the present embodiment, and can be easily manufactured, for example, by the following manufacturing method of the multilayer printed wiring board of the present embodiment.

A method for producing a multilayer printed wiring board using the photosensitive resin film (photosensitive resin film for interlayer insulating layer) of this embodiment will be described with reference to FIG. 1 as appropriate.
The multilayer printed wiring board 100A can be manufactured, for example, by a manufacturing method including the following steps (1) to (4).
Step (1): A step of laminating the photosensitive resin film of the present embodiment onto one or both sides of a circuit board (hereinafter also referred to as "lamination step (1)").
Step (2): A step of forming an interlayer insulating layer having vias by exposing and developing the photosensitive resin film laminated in step (1) (hereinafter also referred to as "lamination step (2)").
Step (3): A step of roughening the vias and the interlayer insulating layer (hereinafter also referred to as "roughening step (3)").
Step (4): A step of forming a circuit pattern on the interlayer insulating layer (hereinafter, also referred to as "circuit pattern forming step (4)").

(Lamination process (1))
The lamination step (1) is a step of laminating the photosensitive resin film of this embodiment (photosensitive resin film for interlayer insulating layer) on one or both sides of a circuit board (substrate 101 having a circuit pattern 102) using, for example, a vacuum laminator. Examples of the vacuum laminator include a vacuum applicator manufactured by Nichigo-Morton Co., Ltd., a vacuum pressure laminator manufactured by Meiki Co., Ltd., a roll-type dry coater manufactured by Hitachi, Ltd., and a vacuum laminator manufactured by Hitachi Chemical Electronics Co., Ltd.

When a protective film is provided on the photosensitive resin film, after peeling or removing the protective film, the photosensitive resin film can be laminated by being pressed and heated onto the circuit board so that the photosensitive resin film is in contact with the circuit board.
The lamination can be carried out, for example, after preheating the photosensitive resin film and the circuit board as necessary, under reduced pressure at a pressure of 70 to 130° C., a pressure of 0.1 to 1.0 MPa, and an air pressure of 20 mmHg (26.7 hPa) or less, but is not particularly limited to these conditions. The lamination method may be a batch method or a continuous method using a roll.
Finally, the photosensitive resin film (hereinafter sometimes referred to as the photosensitive layer) laminated to the circuit board is cooled to about room temperature to form the interlayer insulating layer 103. The carrier film may be peeled off at this point, or may be peeled off after exposure as described below.

(Photovia Forming Process (2))
In the photovia forming process (2), at least a part of the photosensitive resin film laminated on the circuit board is exposed to light, and then developed. By exposure, the part irradiated with active light is photocured to form a pattern. There is no particular limitation on the exposure method, and for example, a method of irradiating active light in an image-like manner through a negative or positive mask pattern called artwork (mask exposure method) may be adopted, or a method of irradiating active light in an image-like manner by a direct imaging exposure method such as LDI (Laser Direct Imaging) exposure method or DLP (Digital Light Processing) exposure method may be adopted.

A known light source can be used as the light source of the actinic rays. Specific examples of the light source include gas lasers such as carbon arc lamps, mercury vapor arc lamps, high-pressure mercury lamps, xenon lamps, and argon lasers; solid-state lasers such as YAG lasers; and those that effectively emit ultraviolet or visible light such as semiconductor lasers. The exposure amount is appropriately selected depending on the light source used and the thickness of the photosensitive layer, and for example, in the case of ultraviolet irradiation from a high-pressure mercury lamp, when the photosensitive layer has a thickness of 1 to 100 μm, it is usually preferably about 10 to 1,000 J/m ² , and more preferably 15 to 500 J/m ² .

In the development, the uncured portions of the photosensitive layer are removed from the substrate, and an interlayer insulating layer made of a photocured product is formed on the substrate.
When a carrier film is present on the photosensitive layer, the carrier film is removed before removing (developing) the unexposed portion. The developing method includes wet development and dry development, either of which may be adopted, but wet development is widely used and can be adopted in this embodiment as well.

In the case of wet development, a developer corresponding to the photosensitive resin composition is used to develop the photosensitive resin composition by a known development method. Examples of the development method include a dip method, a bath method, a spray method, a brushing method, a slapping method, a scraping method, a swing immersion method, and the like. Among them, from the viewpoint of improving the resolution, the spray method is preferred, and among the spray methods, the high pressure spray method is more preferred. The development may be performed by one method, or may be performed by combining two or more methods.
The composition of the developer may be appropriately selected depending on the composition of the photosensitive resin composition. For example, an alkaline aqueous solution, a water-based developer, or an organic solvent-based developer may be used, and among these, an alkaline aqueous solution is preferred.

In the photovia formation process (2), after exposure and development, a post UV cure with an exposure amount of about 0.2 to 10 J/ ^cm2 (preferably 0.5 to 5 J/ ^cm2 ) and a post thermal cure at a temperature of about 60 to 250°C (preferably 120 to 200°C) may be performed as necessary to further harden the interlayer insulating layer, and it is preferable to do so.
In this manner, an interlayer insulating layer having vias 104 is formed. There are no particular limitations on the shape of the vias, and examples of the cross-sectional shape include a rectangle and an inverted trapezoid (the upper side is longer than the lower side), and examples of the shape as viewed from the front (the direction in which the via bottom is visible) include a circle and a rectangle. In the formation of vias by photolithography in this embodiment, a via having a cross-sectional shape of an inverted trapezoid (the upper side is longer than the lower side) can be formed, which is preferable because it increases the adhesion of plated copper to the via wall surface.

The size (diameter) of the via formed by this process can be less than 40 μm, and can also be 35 μm or less or 30 μm or less, which is smaller than the size of the via formed by laser processing. There is no particular limit to the lower limit of the size (diameter) of the via formed by this process, but it may be 15 μm or more, or 20 μm or more.
However, the size (diameter) of the vias formed by this process is not limited to less than 40 μm, and may be, for example, approximately 200 μm or less.

(Roughening treatment step (3))
In the roughening process (3), the surface of the via and the interlayer insulating layer is roughened with a roughening liquid. If a smear occurs in the photovia forming process (2), the smear may be removed with the roughening liquid. The roughening process and the removal of the smear can be performed simultaneously.
Examples of the roughening solution include a chromium/sulfuric acid roughening solution, an alkaline permanganate roughening solution (for example, a sodium permanganate roughening solution), and a sodium fluoride/chromium/sulfuric acid roughening solution.
The roughening treatment forms uneven anchors on the surface of the via and the interlayer insulating layer.

(Circuit pattern formation process (4))
The circuit pattern forming step (4) is a step of forming a circuit pattern on the interlayer insulating layer after the roughening treatment step (3).
From the viewpoint of forming fine wiring, it is preferable to form the circuit pattern by a semi-additive process, which forms the circuit pattern and also provides electrical continuity of the vias.

In the semi-additive process, first, the via bottom, via wall, and the entire surface of the interlayer insulating layer after the roughening process (3) are subjected to electroless copper plating using a palladium catalyst or the like to form a seed layer 105. The seed layer is intended to form a power supply layer for electrolytic copper plating, and is preferably formed to a thickness of about 0.1 to 2.0 μm. If the seed layer is 0.1 μm or more thick, it tends to be possible to suppress a decrease in connection reliability during electrolytic copper plating, and if it is 2.0 μm or less, there is no need to increase the amount of etching when flash etching the seed layer between wiring, and damage to the wiring during etching tends to be suppressed.

The electroless copper plating process is carried out by reacting copper ions with a reducing agent to deposit metallic copper on the surface of the vias and the interlayer insulating layer.
The electroless plating method and the electrolytic plating method may be known methods and are not particularly limited, but the catalyst in the electroless plating step is preferably a palladium-tin mixed catalyst, and the primary particle size of the catalyst is preferably 10 nm or less. In addition, the plating composition in the electroless plating step preferably contains hypophosphorous acid as a reducing agent.
As the electroless copper plating solution, a commercially available product can be used. Examples of commercially available products include "MSK-DK" manufactured by Atotech Japan KK and "ThruCup (registered trademark) PEA ver. 4" manufactured by Uemura Kogyo Co., Ltd.

After the electroless copper plating process, a dry film resist is heat-pressed onto the electroless copper plating using a roll laminator. The thickness of the dry film resist must be greater than the wiring height after electrolytic copper plating, and from this viewpoint, a dry film resist having a thickness of 5 to 30 μm is preferred. As the dry film resist, the "Photec" series manufactured by Hitachi Chemical Co., Ltd., or the like is used.
After the dry film resist is thermocompressed, the dry film resist is exposed to light, for example, through a mask on which a desired wiring pattern is drawn. The exposure can be performed using the same device and light source as those that can be used when forming vias in the photosensitive resin film. After the exposure, the carrier film on the dry film resist is peeled off, and development is performed using an alkaline aqueous solution to remove the unexposed parts, forming a resist pattern 106. Thereafter, if necessary, a work of removing development residues of the dry film resist using plasma or the like may be performed.
After development, copper electroplating is performed to form a copper circuit layer 107 and fill vias.

After electrolytic copper plating, the dry film resist is stripped using an alkaline aqueous solution or an amine-based stripper. After the dry film resist is stripped, the seed layer between the wiring is removed (flash etching). Flash etching is performed using an acidic solution such as sulfuric acid and hydrogen peroxide, and an oxidizing solution. Specific examples include "SAC" manufactured by JCU Corporation and "CPE-800" manufactured by Mitsubishi Gas Chemical Company, Inc. After flash etching, palladium and other materials adhering to the portions between the wiring are removed as necessary. Palladium can be removed preferably using an acidic solution such as nitric acid or hydrochloric acid.

After the dry film resist is peeled off or after the flash etching step, a post-baking process is preferably performed. The post-baking process sufficiently heat-cures unreacted thermosetting components, thereby improving the adhesive strength with plated copper, the insulation reliability, and the curing characteristics. The thermosetting conditions vary depending on the type of resin composition, but a curing temperature of 150 to 240°C and a curing time of 15 to 100 minutes are preferred. The post-baking process completes the manufacturing process for a printed wiring board using the photovia method, but this process is repeated to manufacture a board according to the number of interlayer insulating layers required. Then, a solder resist layer 108 is preferably formed as the outermost layer.

[Semiconductor package]
The semiconductor package of this embodiment is obtained by mounting a conductor element on the multilayer printed wiring board of this embodiment. The semiconductor package of this embodiment can be manufactured, for example, by mounting a semiconductor element such as a semiconductor chip or memory at a predetermined position on the multilayer printed wiring board of this embodiment and sealing the semiconductor element with a sealing resin or the like.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
The properties of the photosensitive resin compositions obtained in the respective examples were evaluated by the methods described below.

1. Evaluation of via resolution (1) Preparation of laminate for evaluation The copper foil surface of a printed wiring board substrate (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-679") in which a 12 μm thick copper foil was laminated on a glass epoxy base material was treated with a roughening pretreatment liquid (manufactured by MEC Co., Ltd., product name "CZ-8100"), and then washed with water and dried to obtain a roughening pretreated printed wiring board substrate. Next, the protective film was peeled off and removed from the carrier film and protective film-attached photosensitive resin film produced in each Example and Comparative Example, and the exposed photosensitive resin film was placed so as to abut against the copper foil of the roughening pretreated printed wiring board substrate, and then a lamination process was performed using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500"). The lamination conditions were: press hot plate temperature 70° C., vacuum time 20 seconds, lamination press time 30 seconds, air pressure 4 kPa or less, and pressure bonding pressure 0.4 MPa. After lamination, the product was left at room temperature for 1 hour or more to obtain a laminate for evaluation in which a photosensitive resin film and a carrier film were laminated in this order on the copper foil surface of the substrate for printed wiring board.
(2) Sensitivity Measurement of Photosensitive Resin Film After peeling and removing the carrier film of the laminate obtained above for evaluation, a 41-step tablet was placed and exposed using a direct imaging exposure device "DXP-3512" (manufactured by Oak Manufacturing Co., Ltd.) with an ultra-high pressure mercury lamp as a light source. The exposure pattern used was a pattern in which dots with diameters of φ30 to 100 μm were arranged in a lattice pattern.
After exposure, the film was left at room temperature for 30 minutes, and then the unexposed portion of the photosensitive resin composition was spray-developed for 60 seconds using a 1% by mass aqueous solution of sodium carbonate at 30° C. After development, the amount of exposure energy at which the gloss remaining step number of the 41-step tablet was 10.0 was defined as the sensitivity of the photosensitive resin film (unit: mJ/cm ² ). Using the pattern exposed at this sensitivity, the resolution of the vias provided in the photosensitive resin film was evaluated according to the following evaluation criteria.
(3) Resolution Evaluation Resolution was evaluated by exposing with an exposure energy amount that results in a step number of 10.0, then spray developing, and observing the via pattern using an optical microscope. The openings of the φ50 μm and φ60 μm vias in the dot pattern were evaluated according to the following criteria. A minimum opening diameter of 60 μm or less, i.e., ratings of "A" and "B", indicates excellent via resolution, and a minimum opening diameter of more than 60 μm or no cured film was obtained, i.e., ratings of "C" and "D", indicates failure.
A: The minimum diameter of the opening was 50 μm or less.
B: The minimum diameter of the opening was more than 50 μm and 60 μm or less.
C: The minimum diameter of the opening was more than 60 μm.
D: No cured film was obtained.

2. Evaluation of adhesive strength (peel strength) with plated copper (1) Preparation of laminate for evaluation and measurement of sensitivity of photosensitive resin film Operations were carried out in the same manner as in (1) and (2) of [1. Evaluation of resolution] above, except that the exposure machine used in the procedures (1) and (2) of [1. Evaluation of resolution] above was changed to a parallel light exposure machine using an ultra-high pressure mercury lamp as the light source (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201"), and the amount of exposure energy at which the gloss remaining step number became 10.0 was determined, and this was defined as the sensitivity (unit: mJ/cm ² ) of the photosensitive resin film.
(2) Exposure Step and Development Step Next, the carrier film of the evaluation laminate was peeled off and the surface of the exposed photosensitive resin film was exposed to light with the amount of exposure energy determined above, and the photosensitive resin film was cured to form an insulating layer. After leaving the film at room temperature for 30 minutes after exposure, the unexposed photosensitive resin film was spray-developed with a 1% by mass aqueous solution of sodium carbonate at 30° C. for 60 seconds.
(3) Post-cure treatment Next, a post-UV cure was performed using a UV conveyor device (manufactured by Oak Manufacturing Co., Ltd.) with a high-pressure mercury lamp irradiation type, at a conveyor speed such that the exposure dose was 2 J/ ^cm2 , and then a post-thermal cure was performed at 170°C for 1 hour using a hot air circulation dryer (manufactured by Futaba Scientific Co., Ltd.).
(4) Roughening Treatment The evaluation laminate after the post-cure treatment was treated with a swelling liquid "Swelling Dip Securigant P" at 70° C. for 5 minutes, then with a roughening liquid "Dosing Securigant P500J" at 70° C. for 10 minutes, and further with a neutralizing liquid "Reduction Conditioner Securigant P500" at 40° C. for 5 minutes to perform a roughening treatment. The swelling liquid, roughening liquid, and neutralizing liquid used were all manufactured by Atotech Japan Co., Ltd.
(5) Plating Treatment The evaluation laminate after the roughening treatment was subjected to electroless plating treatment at 30°C for 20 minutes using an electroless plating solution "Prigant MSK-DK" (manufactured by Atotech Japan Co., Ltd.), and then electroplating treatment was performed at 24°C and 2 A/ ^dm2 for 1 hour using an electroplating solution "Cupracid HL" (manufactured by Atotech Japan Co., Ltd.) to form a plated copper layer on the insulating layer, thereby producing an evaluation board for measuring the adhesive strength with the plated copper. The thickness of the plated copper formed by the plating treatment was 25 μm.
(6) Measurement of Adhesion Strength (Peel Strength) with Plated Copper Adhesion strength with plated copper was measured in accordance with JIS C6481 (1996) by measuring the vertical peel strength at 23°C. The adhesion strength with plated copper was evaluated according to the following criteria. If the adhesion strength with plated copper is 0.40 kN/m or more, it indicates excellent performance, i.e., a rating of "A" indicates excellent adhesion strength with plated copper, and if it is less than 0.40 kN/m, i.e., a rating of "B" or "C", it indicates failure.
A: The adhesive strength to plated copper was 0.40 kN/m or more.
B: The adhesive strength with plated copper was less than 0.40 kN/m and 0.30 kN/m or more.
C: The adhesive strength to plated copper was less than 0.30 kN/m.

Synthesis Example 1 (A1-1) Synthesis of Acid-Modified Vinyl Group-Containing Epoxy Derivative 1 350 parts by mass of bisphenol F novolac epoxy resin (a bisphenol F novolac epoxy resin containing a structural unit in which Y ¹ is a glycidyl group and R ¹ is a hydrogen atom in the above general formula (I), corresponding to component (a1)), 70 parts by mass of acrylic acid (corresponding to component (a2)), 0.5 parts by mass of methylhydroquinone, and 120 parts by mass of carbitol acetate were charged and reacted by heating to 90°C and stirring, until the mixture was completely dissolved.
Next, the obtained solution was cooled to 60° C., 2 parts by mass of triphenylphosphine was added, and the solution was heated to 100° C. and reacted until the acid value of the solution reached 1 mgKOH/g. To the reacted solution, 98 parts by mass of tetrahydrophthalic anhydride (corresponding to component (a3)) and 85 parts by mass of carbitol acetate were added, and the solution was heated to 80° C. and reacted for 6 hours.
Thereafter, the mixture was cooled to room temperature to obtain an acid-modified vinyl group-containing epoxy derivative 1, which was an acid-modified bisphenol F novolac type epoxy acrylate having a solid content of 73% by mass (corresponding to component (A1-1)).

<Method for measuring weight average molecular weight>
The weight average molecular weight was measured using the following GPC measuring device and measuring conditions, and the value converted using the calibration curve of standard polystyrene was defined as the weight average molecular weight. The calibration curve was created using a 5-sample set of standard polystyrene ("PStQuick MP-H" and "PStQuick B", manufactured by Tosoh Corporation).
(GPC measuring device)
GPC device: High-speed GPC device "HCL-8320GPC", detector is differential refractometer or UV, manufactured by Tosoh Corporation Column: Column TSKgel SuperMultipore HZ-H (column length: 15 cm, column inner diameter: 4.6 mm), manufactured by Tosoh Corporation (measurement conditions)
Solvent: Tetrahydrofuran (THF)
Measurement temperature: 40°C
Flow rate: 0.35 ml/min Sample concentration: 10 mg/5 ml THF
Injection volume: 20 μl

Synthesis Example 2 (A1-1) Synthesis of Acid-Modified Vinyl Group-Containing Epoxy Derivative 2 320 parts by mass of cresol novolac resin (EP4020G, manufactured by Asahi Organic Chemicals Co., Ltd.), 925 parts by mass of epichlorohydrin, and 185 parts by mass of n-butanol were dissolved in a flask equipped with a thermometer and a stirrer. After that, the temperature was raised to 65° C. while purging with nitrogen gas, and the pressure was reduced to an azeotropic pressure, and 122 parts by mass of a 49% by mass aqueous sodium hydroxide solution was dropped over 5 hours and stirred for 0.5 hours. During this time, the distillate distilled by azeotropy was separated using a Dean-Stark trap, the water layer was removed, and the organic layer was reacted while being returned to the reaction system. Next, unreacted epichlorohydrin was distilled off under reduced pressure to obtain a crude epoxy resin. 1,000 parts by mass of methyl isobutyl ketone and 100 parts by mass of n-butanol were added to the obtained crude epoxy resin to dissolve it, and 20 parts by mass of a 10% by mass aqueous sodium hydroxide solution was added to this solution and reacted at 80° C. for 2 hours. Thereafter, the mixture was washed three times with 300 parts by mass of water, and it was confirmed that the pH of the washing liquid was neutral.
Next, the system was dehydrated by azeotropy, and the solvent was distilled off under reduced pressure after microfiltration to obtain a transparent liquid epoxy resin a-1: 350 parts by mass. Subsequently, 70 parts by mass of acrylic acid (b), 0.5 parts by mass of methyl hydroquinone, and 120 parts by mass of carbitol acetate were charged, and the mixture was reacted by heating to 90 ° C. and stirring, and the mixture was completely dissolved. The obtained solution was cooled to 60 ° C., 2 parts by mass of triphenylphosphine was added, and the mixture was heated to 100 ° C. and reacted until the acid value of the solution became 1 mgKOH / g, to which 98 parts by mass of tetrahydrophthalic anhydride (THPAC) (c) and 850 parts by mass of carbitol acetate were added, and the mixture was heated to 80 ° C. and reacted for 6 hours. Thereafter, the mixture was cooled to room temperature, and a THPAC-modified cresol novolac-type epoxy acrylate epoxy resin having a solid content concentration of 73 mass% was obtained as an acid-modified vinyl group-containing epoxy derivative 2.

<Examples 1 to 5, Comparative Examples 1 and 2>
(Preparation of Photosensitive Resin Composition)
Photosensitive resin compositions were prepared by mixing the components according to the formulation shown in Table 1 using a three-roll mill. In each example, carbitol acetate was appropriately added to adjust the concentration, and a photosensitive resin composition having a solid content of 60% by mass was obtained.
(Preparation of Photosensitive Resin Film)
A 25 μm thick polyethylene terephthalate film (G2-16, Teijin Limited, product name) was used as a carrier film, and the photosensitive resin composition prepared in each example was applied onto the carrier film so that the film thickness after drying was 25 μm, and dried for 10 minutes at 100° C. using a hot air convection dryer to form a photosensitive resin film (photosensitive layer). Next, a biaxially oriented polypropylene film (MA-411, Oji F-Tex Co., Ltd., product name) was laminated as a protective film onto the surface of the photosensitive resin film (photosensitive layer) opposite to the side in contact with the carrier film, to produce a photosensitive resin film in which the carrier film and protective film were laminated together.
The photosensitive resin film thus produced was subjected to the various evaluations according to the above-mentioned methods. The evaluation results are shown in Table 1.

The components used in each example are as follows:
Component (A): a photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton. Acid-modified vinyl group-containing epoxy derivative 1: obtained in Synthesis Example 1 above (corresponding to component (A1-1)).
Acid-modified vinyl group-containing epoxy derivative 2: This was obtained in Synthesis Example 2 above (corresponding to component (A1-1)).
- Multifunctional vinyl monomer: dipentaerythritol pentaacrylate (corresponding to component (Aiii))
Component (B): Photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton. Isocyanuric acid acrylate 1: Tris(2-acryloyloxyethyl) isocyanurate ("FA-731A" (manufactured by Hitachi Chemical Co., Ltd.))
Isocyanuric acid acrylate 2: Tris(2-acryloyloxyethyl) isocyanurate ("A-9300" (manufactured by Shin-Nakamura Chemical Co., Ltd.))
Isocyanuric acid acrylate 3: EO-modified isocyanuric acid di- and triacrylate ("ARONIX M-315" (manufactured by Toagosei Co., Ltd.))
Component (C): Photopolymerization initiator Photopolymerization initiator 1: Acetophenone-based photopolymerization initiator (2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, "IRGACURE 907" (manufactured by BASF))
Photopolymerization initiator 2: Thioxanthone-based photopolymerization initiator (2,4-diethylthioxanthone, "KAYACURE DETX-S" (manufactured by Nippon Kayaku Co., Ltd.))
Component (D): Thermosetting resin/epoxy resin: biphenyl type epoxy resin ("YX-4000" (manufactured by Mitsubishi Chemical Corporation))
Component (E): Elastomer Elastomer 1: Epoxidized polybutadiene ("PB-4700" (manufactured by Daicel Corporation))
Elastomer 2: Polyester resin ("Espel 1108" (Hitachi Chemical Co., Ltd.))
(F) Component: Inorganic filler Silica: Silica particles (average particle size: 1.3 μm, "CRS-2101-41" (manufactured by Tatsumori Co., Ltd.))

The photosensitive resin composition of this embodiment was confirmed to have excellent via resolution and adhesive strength with plated copper. On the other hand, the resin composition of Comparative Example 1, which does not contain component (B), had poor adhesive strength with plated copper, and the resin composition of Comparative Example 2, which does not contain a photopolymerization initiator, had poor via resolution and adhesive strength with plated copper.

100A Multilayer printed wiring board 101 Substrate 102 Circuit pattern 103 Interlayer insulating layer 104 Via (via hole)
105 seed layer 106 resist pattern 107 copper circuit layer 108 solder resist layer

Claims (14)

A photosensitive resin composition comprising: (A) a photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton; (B) a photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton (excluding imide resins having a vinyl group); (C) a photopolymerization initiator; (D) a thermosetting resin ; (E) an elastomer; and (F) an inorganic filler;
The content of the inorganic filler (F) is 25 to 80 mass% based on the total solid content,
the (B) photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton (excluding imide resins having a vinyl group) is at least one selected from the group consisting of di(2-(meth)acryloyloxyethyl) isocyanurate, tri(2-(meth)acryloyloxyethyl) isocyanurate, and alkylene oxide modified products thereof;
the (D) thermosetting resin is a biphenyl-type epoxy resin,
the (A) photopolymerizable compound having an ethylenically unsaturated group and no isocyanuric skeleton comprises (A1) a photopolymerizable compound having an acidic substituent together with an ethylenically unsaturated group and no isocyanuric skeleton, and (Aiii) a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups (excluding the (A1) component);
the (A1) photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and having no isocyanuric skeleton is (A1-1) an acid-modified vinyl-group-containing epoxy resin derivative obtained by reacting (a1) an epoxy resin modified with (a2) a vinyl-group-containing organic acid with (a3) a saturated or unsaturated group-containing polybasic acid anhydride,
The photosensitive resin composition, wherein the inorganic filler (F) is silica. The photosensitive resin composition according to claim 1, wherein the (B) photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton (excluding imide resins having a vinyl group) is at least one selected from the group consisting of tri(2-(meth)acryloyloxyethyl)isocyanurate and its alkylene oxide modified derivatives. The photosensitive resin composition according to claim 1 or 2, wherein the content of the thermosetting resin (D) is 5 to 70 mass % based on the total amount of the resin components of the photosensitive resin composition. The photosensitive resin composition according to any one of claims 1 to 3, wherein the content of the photopolymerizable compound (A) having an ethylenically unsaturated group and not having an isocyanuric skeleton is 5 to 60 mass% based on the total solid content. The photosensitive resin composition according to any one of claims 1 to 4, wherein the content of (B) the photopolymerizable compound having an ethylenically unsaturated group and an isocyanuric skeleton (excluding imide resins having vinyl groups) is 0.5 to 15 mass% based on the total solid content. The photosensitive resin composition according to any one of claims 1 to 5, wherein the content of the photopolymerization initiator (C) is 0.1 to 15 mass% based on the total solid content. The photosensitive resin composition according to any one of claims 1 to 6, which is used for forming photovias. The photosensitive resin composition according to any one of claims 1 to 7, which is used to form an interlayer insulating layer. A photosensitive resin film comprising the photosensitive resin composition according to any one of claims 1 to 8. The photosensitive resin film according to claim 9, which is used to form an interlayer insulating layer. A multilayer printed wiring board having an interlayer insulating layer formed using the photosensitive resin composition according to any one of claims 1 to 6. A multilayer printed wiring board having an interlayer insulating layer formed using the photosensitive resin film according to claim 9. A semiconductor package comprising a semiconductor element mounted on the multilayer printed wiring board according to claim 11 or 12. A method for producing a multilayer printed wiring board comprising the following steps (1) to (4) in order:
Step (1): A step of laminating the photosensitive resin film according to claim 9 onto one or both sides of a circuit board.
Step (2): A step of forming an interlayer insulating layer having vias by exposing and developing the photosensitive resin film laminated in the step (1).
Step (3): A step of roughening the via and the interlayer insulating layer.
Step (4): forming a circuit pattern on the interlayer insulating layer.