JP7654944B2 - Photosensitive resin composition, photosensitive resin film, multilayer printed wiring board and 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 and a semiconductor package, and a method for manufacturing a multilayer printed wiring board.

In recent years, electronic devices have become smaller and more powerful, and multilayer printed wiring boards are becoming increasingly 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 vias (also called "via holes") for interlayer connection. In addition, as the insulating films in printed wiring boards become thinner, there is also a demand for excellent interlayer electrical insulation reliability [particularly electrical insulation reliability after moisture absorption (HAST (High Accelerated Stress Test) resistance)].

As a method for manufacturing a printed wiring board, there is a method for manufacturing a multilayer printed wiring board by 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 the multilayer printed wiring board. As circuits become finer, a semi-additive method in which the circuits are formed by plating has become mainstream for multilayer printed wiring boards.
In the conventional semi-additive method, for example, (1) a thermosetting resin film is laminated on a conductor circuit, and the thermosetting resin film is cured by heating to form an "interlayer insulating layer". (2) Next, vias for interlayer connection are formed by laser processing, and desmearing and roughening are performed by alkaline permanganate treatment or the like. (3) After that, electroless copper plating is performed on the substrate, and a pattern is formed using a resist, followed by electrolytic copper plating to form a copper circuit layer. (4) Next, the resist is stripped, and the electroless layer is flash etched to form a copper circuit.

As mentioned above, laser processing is the mainstream method for forming vias in an interlayer insulating layer formed by hardening a thermosetting resin film, but the reduction in the diameter of vias by laser irradiation using a laser processing machine has reached 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 increase density, it takes a long time to form the vias, resulting in poor manufacturing efficiency.

Under these circumstances, a method has been proposed that can form a large number of vias at once, in which a photosensitive resin composition containing (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, in which the content of the inorganic filler (D) is 10 to 80 mass %, is used to form a large number of small vias at once by photolithography (see, for example, Patent Document 2).

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

In Patent Document 2, one of the problems is 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 further, the resolution of vias and adhesion with a silicon substrate and chip parts are also problems, and it is said that these problems have been solved. However, in addition to further miniaturization of wiring, the insulating film is thinned and the diameter of via holes for interlayer connection is reduced, so there is a growing demand for improvement in adhesive strength with plated copper and electrical insulation reliability. In order to miniaturize wiring, the surface of the insulating film is required to have a low roughness, but if the roughness is low, the adhesive strength with plated copper is reduced, so there is a trade-off between miniaturization of wiring and adhesive strength with plated copper. In terms of increasing adhesive strength with plated copper while having a low roughness and electrical insulation reliability, there is room for further improvement in the photosensitive resin composition of Patent Document 2.
Similarly, it is conceivable that photosensitive resin compositions, which are conventional materials for solder resists, could be used as materials for the interlayer insulating layer. However, since interlayer insulating layers require properties that were not necessary for solder resists (e.g., reliable electrical insulation between layers, adhesive strength with plated copper, high heat resistance capable of withstanding multiple heating processes, high dimensional accuracy of the via shapes, etc.), it is difficult to predict whether they would be practical to use as interlayer insulating layers, and they cannot be easily used.

The object of the present invention is to provide a photosensitive resin composition, a photosensitive resin composition for forming photovias, and a photosensitive resin composition for an interlayer insulating layer, which have high via resolution, low roughness, high adhesive strength with plated copper, and excellent electrical insulation reliability. It is also an object of the present invention to provide a photosensitive resin film and a photosensitive resin film for an interlayer insulating layer made of the photosensitive resin composition, to provide a multilayer printed wiring board and a semiconductor package, and to provide a method for manufacturing the multilayer printed wiring board.

As a result of extensive research, the inventors have found that the above-mentioned object can be achieved by the following invention. That is, the present invention relates to the following [1] to [19].

[1] A photosensitive resin composition comprising (A) a photopolymerizable compound having an ethylenically unsaturated group, (B) a photopolymerization initiator, (C) a benzoxazine compound, and (D) a thermosetting resin,
The photosensitive resin composition, wherein the (A) photopolymerizable compound having an ethylenically unsaturated group includes at least one selected from the group consisting of (A1) photopolymerizable compounds having an acidic substituent and an alicyclic skeleton together with an ethylenically unsaturated group, and (A2-1) acid-modified ethylenically unsaturated group-containing epoxy derivatives not containing an alicyclic skeleton.
[2] The photosensitive resin composition according to the above [1], wherein the (C) benzoxazine compound has 1 to 3 benzoxazine rings in its molecular structure.
[3] The photosensitive resin composition according to the above [1] or [2], wherein the (C) benzoxazine compound is a benzoxazine compound represented by any one of the following general formulas (C-1) to (C-3):

(In the formula, R ^c1 and R ^c2 each independently represent a hydrocarbon group having 1 to 10 carbon atoms. X ^c1 represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)-, or a single bond. n ^c1 and n ^c2 each independently represent an integer of 0 to 4.)

(In the formula, each R ^c3 is independently a hydrocarbon group having 1 to 10 carbon atoms. Each R ^c4 is independently a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. Each ^{X c2} is a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)- or a single bond. Each ^{n c3} is independently an integer of 0 to 3.)

(In the formula, R ^c5 is a hydrocarbon group having 1 to 10 carbon atoms. R ^c6 is a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. n ^c4 is an integer of 0 to 4.)
[4] The photosensitive resin composition according to any one of [1] to [3] above, wherein the content of the (C) benzoxazine compound is 0.5 to 30 mass% based on the total solid content of the photosensitive resin composition.
[5] The photosensitive resin composition according to any one of the above [1] to [4], wherein in the photopolymerizable compound (A1) having an ethylenically unsaturated group, an acidic substituent, and an alicyclic skeleton, the alicyclic skeleton is an alicyclic skeleton having 5 to 20 ring carbon atoms.
[6] The photosensitive resin composition according to any one of the above [1] to [5], wherein in the (A1) photopolymerizable compound having an ethylenically unsaturated group, an acidic substituent, and an alicyclic skeleton, the alicyclic skeleton has two or more rings.
[7] The photosensitive resin composition according to any one of the above [1] to [6], wherein the (A) photopolymerizable compound having an ethylenically unsaturated group further comprises at least one selected from the group consisting of (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.
[8] The photosensitive resin composition according to any one of the above [1] to [7], wherein the (D) thermosetting resin is at least one selected from the group consisting of an epoxy resin, a phenolic resin, an unsaturated imide resin, a cyanate resin, an isocyanate resin, a benzoxazine resin, an oxetane resin, an amino resin, an unsaturated polyester resin, an allyl resin, a dicyclopentadiene resin, a silicone resin, a triazine resin, and a melamine resin.
[9] The photosensitive resin composition according to any one of the above [1] to [8], further comprising (E) an elastomer.
[10] The photosensitive resin composition according to the above [9], wherein the (E) elastomer comprises at least one selected from the group consisting of a styrene-based elastomer, an olefin-based elastomer, a polyester-based elastomer, a urethane-based elastomer, a polyamide-based elastomer, an acrylic-based elastomer, and a silicone-based elastomer.
[11] The photosensitive resin composition according to any one of the above [1] to [10], further comprising (F) an inorganic filler.
[12] A photosensitive resin composition for forming a photovia, comprising the photosensitive resin composition according to any one of [1] to [11] above.
[13] A photosensitive resin composition for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of [1] to [11] above.
[14] A photosensitive resin film comprising the photosensitive resin composition according to any one of [1] to [11] above.
[15] A photosensitive resin film for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of [1] to [11] above.
[16] A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin composition according to any one of [1] to [11] above.
[17] A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin film according to [14] above.
[18] A semiconductor package comprising the multilayer printed wiring board according to [16] or [17] above and a semiconductor element mounted thereon.
[19] A method for producing a multilayer printed wiring board, comprising the following steps (1) to (4):
Step (1): A step of laminating the photosensitive resin film according to the above item [14] 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, a photosensitive resin composition for forming photovias, and a photosensitive resin composition for an interlayer insulating layer, which have high via resolution, high adhesive strength to plated copper while having low roughness, and excellent electrical insulation reliability. It is also possible to provide a photosensitive resin film and a photosensitive resin film for an interlayer insulating layer made of the photosensitive resin composition, and to provide a multilayer printed wiring board and a semiconductor package containing an interlayer insulating layer formed using the photosensitive resin composition or the photosensitive resin film.
Furthermore, it is possible to provide a method for efficiently manufacturing a multilayer printed wiring board having high-resolution vias, high adhesive strength between an interlayer insulating layer and plated copper, and excellent electrical insulation reliability. The vias in the multilayer printed wiring board obtained by the manufacturing method of the present invention can be smaller in diameter than vias formed by laser processing.

2A to 2C are schematic diagrams illustrating an embodiment of a process for producing a multilayer printed wiring board according to the present invention.

In the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with the values shown in the examples. In addition, the lower and upper limits of the numerical ranges may be arbitrarily combined with the lower or upper limit of other numerical ranges.
Furthermore, in this specification, when there are multiple substances corresponding to each component in the photosensitive resin composition, the content of each component means the total content of the multiple substances present in the photosensitive resin composition, unless otherwise specified.
In this specification, the term "number of ring carbon atoms" refers to the number of carbon atoms necessary to form a ring, and does not include the number of carbon atoms of the substituents on the ring. For example, both the cyclohexane skeleton and the methylcyclohexane skeleton have 6 ring carbon atoms.
The expression "(meth)acrylic XX" means one or both of acrylic XX and the corresponding methacrylic XX. In addition, the expression "(meth)acryloyl group" means one or both of an acryloyl group and a methacryloyl group.
Additionally, any combination of the descriptions in this specification is also included in the present invention.

[Photosensitive resin composition, photosensitive resin composition for forming photovias, and photosensitive resin composition for interlayer insulating layer]
A photosensitive resin composition according to one embodiment of the present invention (hereinafter may be simply referred to as this embodiment) is a photosensitive resin composition containing (A) a photopolymerizable compound having an ethylenically unsaturated group, (B) a photopolymerization initiator, (C) a benzoxazine compound, and (D) a thermosetting resin, wherein the (A) photopolymerizable compound having an ethylenically unsaturated group includes at least one selected from the group consisting of (A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton, and (A2-1) an acid-modified ethylenically unsaturated group-containing epoxy derivative that does not contain an alicyclic skeleton.
In this specification, the components may be referred to as component (A), component (B), component (C), component (D), etc., and other components may be abbreviated in the same manner. In this specification, the "resin component" refers to the components (A), (B), (C), and (D), etc., and also includes other components that may be contained as necessary (for example, component (E), etc.), but does not include inorganic compounds such as inorganic fillers (F) and pigments (G) that may be contained as necessary, which will be described later. In addition, the "solid content" refers to the non-volatile content excluding volatile substances such as water and solvents contained in the photosensitive resin composition, and indicates the components that remain without volatilization when the resin composition is dried, and also includes liquid, starch syrup, and wax-like substances at room temperature around 25°C.

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. The photosensitive resin composition of this embodiment also provides a photosensitive resin composition for interlayer insulation layer, because it has high via resolution, low roughness, high adhesive strength with plated copper, and excellent electrical insulation reliability, and is useful as an interlayer insulation layer of a multilayer printed wiring board. In this specification, the photosensitive resin composition includes a photosensitive resin composition for photovia formation and a photosensitive resin composition for interlayer insulation layer.
The photosensitive resin composition of the present embodiment is useful as a negative photosensitive resin composition.
Each component that the photosensitive resin composition may contain will be described in detail below.

<(A) Photopolymerizable compound having an ethylenically unsaturated group>
From the viewpoint of adhesive strength with plated copper, the photosensitive resin composition of the present embodiment contains a photopolymerizable compound having an ethylenically unsaturated group as component (A). Examples of the ethylenically unsaturated group contained in component (A) include a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, and a (meth)acryloyl group. As the ethylenically unsaturated group, a (meth)acryloyl group is preferable.
In the present invention, the component (A) comprises at least one selected from the group consisting of "(A1) a photopolymerizable compound having an acidic substituent and an alicyclic skeleton together with an ethylenically unsaturated group" described below, and "(A2-1) an acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton" described below. In this way, by including at least one of the components (A1) and (A2-1) in the component (A), a photosensitive resin composition excellent in via resolution, adhesive strength to plated copper, and electrical insulation reliability can be obtained.
The components will be described in detail below, beginning with component (A1).

((A1) Photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton)
Examples of the ethylenically unsaturated group contained in the component (A1) include the same ethylenically unsaturated groups as those described above, and are preferably at least one selected from the group consisting of a vinyl group, an allyl group, a propargyl group, a butenyl group, an ethynyl group, a phenylethynyl group, a maleimide group, a nadimide group, and a (meth)acryloyl group, more preferably a vinyl group, an allyl group, or a (meth)acryloyl group, and even more preferably a (meth)acryloyl group.
The acidic substituent contained in the component (A1) is preferably at least one selected from the group consisting of a carboxyl group, a sulfonic acid group, a phenolic hydroxyl group, and the like, and more preferably a carboxyl group.

As the alicyclic skeleton of the component (A1), from the viewpoints of via resolution, adhesive strength to plated copper, and electrical insulation reliability, an alicyclic skeleton having 5 to 20 ring carbon atoms is preferred, an alicyclic skeleton having 5 to 18 ring carbon atoms is more preferred, an alicyclic skeleton having 6 to 18 ring carbon atoms is even more preferred, an alicyclic skeleton having 8 to 14 ring carbon atoms is particularly preferred, and an alicyclic skeleton having 8 to 12 ring carbon atoms is most preferred.
From the viewpoints of via resolution, adhesive strength with plated copper, and electrical insulation reliability, the alicyclic skeleton preferably consists of two or more rings, more preferably two to four rings, and even more preferably three rings. Examples of alicyclic skeletons with one ring include a cyclohexane skeleton and a cyclohexene skeleton. Examples of alicyclic skeletons with two or more rings include a norbornane skeleton, a decalin skeleton, a bicycloundecane skeleton, and a saturated dicyclopentadiene skeleton.
As the alicyclic skeleton, from the viewpoints of via resolution, adhesive strength with plated copper, and electrical insulation reliability, a saturated dicyclopentadiene skeleton is preferable, and an alicyclic skeleton represented by the following general formula (a) (saturated dicyclopentadiene skeleton) is more preferable.

(In general formula (a), R ^A1 represents an alkyl group having 1 to 12 carbon atoms and may be substituted anywhere in the alicyclic skeleton. ^{m 1} is an integer of 0 to 6. * represents a bonding site to another structure.)

In general formula (a), examples of the alkyl group having 1 to 12 carbon atoms represented by R ^A1 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, etc. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is further preferable.
^m1 is an integer of 0 to 6, preferably an integer of 0 to 2, and more preferably 0.
When ^m1 is an integer of 2 to 6, the multiple R ^A1 may be the same or different from each other. Furthermore, the multiple R ^A1 may be substituted on the same carbon atom or on different carbon atoms, to the extent possible.
* represents a bonding site to another structure, and may be bonded to any carbon atom on the alicyclic skeleton. However, it is preferable that the bond is bonded to a carbon atom represented by 1 or 2 and a carbon atom represented by any of 3 to 5 in the following general formula (a').

(In general formula (a'), R ^A1 , ^m1 and * are the same as those in general formula (a).)

Examples of the component (A1) include:
"(A1-1) Acid-modified ethylenically unsaturated group and alicyclic skeleton-containing epoxy derivative" obtained by reacting (a1) an alicyclic skeleton-containing epoxy resin with (a2) an ethylenically unsaturated group-containing organic acid [hereinafter sometimes referred to as component (A')] with (a3) a saturated group- or unsaturated group-containing polybasic acid anhydride;
"(A1-2) Acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing phenol novolac or cresol novolac resin" obtained by reacting (a2) an ethylenically unsaturated group-containing organic acid and (a4) an alicyclic skeleton-containing and saturated or unsaturated group-containing polybasic acid anhydride with a modified novolac epoxy resin obtained by addition polymerization of at least one selected from the group consisting of ethylene oxide and propylene oxide with a phenol novolac resin or cresol novolac resin;
etc.
As the component (A1), the above-mentioned "(A1-1) acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative" is preferred from the viewpoints of alkali developability, and excellent via resolution, adhesive strength to plated copper, and electrical insulation reliability.
First, the raw materials that can be used in the production of "(A1-1) an acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative" will be described in detail.

--(a1) Alicyclic skeleton-containing epoxy resin--
The (a1) alicyclic skeleton-containing 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.

In the present invention, the epoxy resin used is at least an epoxy resin having an alicyclic skeleton. The alicyclic skeleton is explained in the same manner as the alicyclic skeleton of the component (A1) described above, and the preferred embodiments are also the same.
The (a1) alicyclic skeleton-containing epoxy resin is preferably an epoxy resin represented by the following general formula (a1-1): Also preferred is an epoxy resin having a structural unit represented by the following general formula (a1-2):

(In general formula (a1-1), R ^A1 represents an alkyl group having 1 to 12 carbon atoms and may be substituted anywhere in the alicyclic skeleton. ^{R A2} represents an alkyl group having 1 to 12 carbon atoms. ^{m 1} is an integer of 0 to 6, m ² is an integer of 0 to 3, and n is an integer of 0 to 10.)

(In general formula (a1-2), R ^A1 represents an alkyl group having 1 to 12 carbon atoms and may be substituted anywhere in the alicyclic skeleton. m ¹ is an integer of 0 to 6.)

In the general formulae (a1-1) and (a1-2), R ^A1 is the same as R ^A1 in the general formula (a), and the preferred embodiments are also the same.
Examples of the alkyl group having 1 to 12 carbon atoms represented by ^R in general formula (a1-1) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, etc. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is even more preferable.
In general formulae (a1-1) and (a1-2), ^m1 is the same as ^m1 in general formula (a), and the preferred embodiments are also the same.
In general formula (a1-1), ^m2 represents an integer of 0 to 3, preferably 0 or 1, and more preferably 0.
In general formula (a1-1), n represents the repeating number of the structural unit in parentheses and is 0 to 10. Usually, an epoxy resin is a mixture of structural units in parentheses with different repeating numbers, and in that case, n represents the average value of the mixture. n is preferably 2 to 10.

(a1) As the alicyclic skeleton-containing epoxy resin, commercially available products may be used, such as XD-1000 (trade name, manufactured by Nippon Kayaku Co., Ltd.), EPICLON HP-7200L, EPICLON HP-7200, EPICLON HP-7200HH, and EPICLON HP-7200HHH (trade name, manufactured by DIC Corporation, "EPICLON" is a registered trademark), etc.

(a1) As the epoxy resin, epoxy resins other than the epoxy resin having an alicyclic skeleton (hereinafter sometimes referred to as other epoxy resins) may be used in combination. Other epoxy resins include, for example, 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 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; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resin, naphthol novolac type epoxy resin, naphthol type epoxy resin, naphthol aralkyl type epoxy resin, and naphthylene ether type epoxy resin; biphenyl type epoxy resin; xylylene type epoxy resin; dihydroanthracene type epoxy resin; aliphatic chain epoxy resin; and rubber-modified epoxy resin.

-(a2) Ethylenically unsaturated group-containing organic acid-
The (a2) ethylenically unsaturated group-containing organic acid is not particularly limited, but is preferably an ethylenically unsaturated group-containing monocarboxylic acid. The ethylenically unsaturated group is as described for the ethylenically unsaturated group in the (A1) component.
Examples of the ethylenically unsaturated group-containing monocarboxylic acid include acrylic acid, acrylic acid derivatives such as dimers of acrylic acid, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, and α-cyanocinnamic acid, half-ester compounds which are reaction products of hydroxyl group-containing acrylates and dibasic acid anhydrides, and half-ester compounds which are reaction products of ethylenically unsaturated group-containing monoglycidyl ethers or ethylenically unsaturated group-containing monoglycidyl esters and dibasic acid anhydrides. Of these, acrylic acid is preferred.
The component (a2) may be used alone or in combination of two or more kinds.

The half-ester compound can be obtained, for example, by reacting a hydroxyl group-containing acrylate, an ethylenically unsaturated group-containing monoglycidyl ether, or an ethylenically unsaturated group-containing monoglycidyl ester with a dibasic acid anhydride in an equimolar ratio.

Examples of the hydroxyl group-containing acrylate, ethylenically unsaturated group-containing monoglycidyl ether, and ethylenically unsaturated group-containing monoglycidyl ester used in the synthesis of the half-ester compound, which is an example of component (a2), include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, glycidyl acrylate, and glycidyl methacrylate.

The dibasic acid anhydride used in the synthesis of the 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.

Although not particularly limited, in the reaction between the (a1) component and the (a2) component, it is preferable to react at a ratio of 0.6 to 1.05 equivalents of the (a2) component per equivalent of the epoxy group of the (a1) component, or a ratio of 0.8 to 1.0 equivalents may be used. By reacting at such a ratio, the photopolymerizability is improved, that is, the photosensitivity is increased, and the resolution of the vias tends to be improved.

The component (a1) and the component (a2) can be reacted by dissolving them in an organic solvent.
Examples of the organic solvent include ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers 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; esters such as ethyl acetate, butyl acetate, butyl cellosolve acetate, and carbitol acetate; aliphatic hydrocarbons such as octane and decane; and petroleum 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 (a1) component and the (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 these, phosphine-based catalysts are preferred, and triphenylphosphine is more preferred.
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). With this amount, the reaction between the components (a1) and (a2) tends to be promoted.

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 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 (a1) component and the (a2) component is preferably 60 to 150°C, more preferably 70 to 120°C, and even more preferably 80 to 110°C.

In this way, it is presumed that the (A') component obtained by reacting the (a1) component with the (a2) component has a hydroxyl group formed by a ring-opening addition reaction between the epoxy group of the (a1) component and the carboxyl group of the (a2) component.

-(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 component (a3) containing a saturated or unsaturated group, 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 form (A1-1) an acid-modified ethylenically unsaturated group and alicyclic skeleton-containing epoxy derivative.

In the reaction between the component (A') and the component (a3), for example, the acid value of the acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy 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 ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative (A1-1) is preferably 20 to 150 mgKOH/g, more preferably 30 to 120 mgKOH/g, and even more preferably 40 to 100 mgKOH/g. When the acid value is 20 mgKOH/g or more, the photosensitive resin composition tends to have excellent solubility in a dilute alkaline solution, 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 component (A') and component (a3) is preferably 50 to 150°C, more preferably 60 to 120°C, and even more preferably 70 to 100°C.

In view of the above, the (A1) photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton is not particularly limited, but is preferably represented by the following general formula (A-1).

(In general formula (A-1), R ^A1 represents an alkyl group having 1 to 12 carbon atoms and may be substituted anywhere in the alicyclic skeleton. R ^A2 represents an alkyl group having 1 to 12 carbon atoms. R ^A3 represents an organic group having an ethylenically unsaturated group, an organic group having an ethylenically unsaturated group and an acidic substituent, or a glycidyl group, and at least one R ^A3 is an organic group having an ethylenically unsaturated group and an acidic substituent. m ¹ is an integer of 0 to 6, m ² is an integer of 0 to 3, and n is 0 to 10.)

R ^A1 , R ^A2 , m ¹ , m ² and n in the general formula (A-1) are the same as those in the general formula (a1-1), and the preferred ones are also the same.
R ^A3 is as defined above, but corresponds to the site formed by the reaction of the glycidyl group in the general formula (a1-1) with the component (a2) and the component (a3), and is defined taking into consideration that some of the glycidyl groups remain unreacted. In other words, the "organic group having an ethylenically unsaturated group" which is an option for R ^A3 is a group derived from the component (a2), and the "organic group having an ethylenically unsaturated group and an acidic substituent" is a group derived from the components (a2) and (a3), and if the components (a2) and (a3) react with all the glycidyl groups in the general formula (a1-1), R ^A3 becomes an "organic group having an ethylenically unsaturated group and an acidic substituent", but the site that has only reacted with the component (a2) becomes an "organic group having an ethylenically unsaturated group", and the site that has not reacted with either the components (a2) or (a3) becomes a "glycidyl group".

Next, raw materials that can be used in the production of the "(A1-2) acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing phenol novolak or cresol novolak resin" will be briefly described.
One of the raw materials is a modified novolac type epoxy resin obtained by addition polymerization of at least one selected from the group consisting of ethylene oxide and propylene oxide to a phenol novolac resin or a cresol novolac resin. It is preferable to use a catalyst for the addition polymerization, and examples of the catalyst include metallic sodium, sodium methoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium phenolate, various Lewis acids, etc.
The weight average molecular weight of the phenol novolac resin and the cresol novolac resin is not particularly limited, but is preferably 500 to 30,000, and more preferably 1,000 to 10,000. In this specification, the weight average molecular weight is a value determined in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.
The reaction temperature is not particularly limited, but the reaction can be carried out at a temperature in the range of 60 to 230°C.
The addition polymerization may be carried out by utilizing or adapting a known method, and is not limited to the above-mentioned method.
By the above addition polymerization, a modified novolac type epoxy resin is obtained.

The "(a2) ethylenically unsaturated group-containing organic acid" to be reacted with the modified novolac type epoxy resin obtained above can be explained in the same manner as in the above-mentioned (a2) ethylenically unsaturated group-containing organic acid.
The alicyclic skeleton contained in "(a4) alicyclic skeleton-containing and saturated or unsaturated group-containing polybasic acid anhydride" to be reacted with the modified novolac epoxy resin obtained above is preferably an alicyclic skeleton having 5 to 20 ring carbon atoms, more preferably an alicyclic skeleton having 5 to 15 ring carbon atoms, still more preferably an alicyclic skeleton having 5 to 10 ring carbon atoms, and particularly preferably an alicyclic skeleton having 5 to 8 ring carbon atoms. The alicyclic skeleton may be one ring or may be one consisting of two or more rings, but is preferably one ring. As the alicyclic skeleton, a cyclohexane skeleton, a cyclohexene skeleton, etc. are preferred, and a cyclohexene skeleton is more preferred.
Examples of the "(a4) alicyclic skeleton-containing and saturated or unsaturated group-containing polybasic acid anhydride" include tetrahydrophthalic anhydride, phthalic anhydride, methyltetrahydrophthalic anhydride, ethyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, ethylhexahydrophthalic anhydride, etc. Among these, tetrahydrophthalic anhydride and phthalic anhydride are preferred, and tetrahydrophthalic anhydride is more preferred.
There are no particular limitations on the conditions for reacting the modified novolac epoxy resin with the ethylenically unsaturated group-containing organic acid (a2) and the alicyclic skeleton-containing, saturated group-containing or unsaturated group-containing polybasic acid anhydride (a4). For example, a method in which the (a2) component is reacted at 20 to 100° C. in the presence of a catalyst as necessary, and then the (a4) component is reacted at 20 to 100° C. may be mentioned.

((A1) Molecular Weight of Photopolymerizable Compound Having an Ethylenically Unsaturated Group, an Acidic Substituent, and an Alicyclic Skeleton)
The weight average molecular weight (Mw) of the component (A1) is preferably 1,000 to 30,000, more preferably 2,000 to 25,000, and even more preferably 3,000 to 18,000. Within this range, the adhesive strength to plated copper, heat resistance, and electrical insulation reliability are improved. In particular, the weight average molecular weight (Mw) of the acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative (A1-1) is preferably within the above range. Here, in this specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) (manufactured by Tosoh Corporation) using a calibration curve of standard polystyrene, and more specifically, a value measured according to the method described below.
<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 ("PStQuick MP-H" and "PStQuick B", manufactured by Tosoh Corporation) as standard polystyrene.
(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

((A2-1) Acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton)
As described above, the (A) photopolymerizable compound having an ethylenically unsaturated group may be in an embodiment including "(A2-1) an acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton". The (A2-1) component is preferably obtained by reacting (a23) a saturated or unsaturated group-containing polybasic acid anhydride with (a21) an epoxy resin (not containing an alicyclic skeleton) modified with (a22) an ethylenically unsaturated group-containing organic acid.

The epoxy resin (a21) is not particularly limited as long as it is an epoxy resin that does not contain an alicyclic skeleton, and examples thereof include 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.
In addition, the (a21) epoxy resin is classified into various epoxy resins depending on the difference in the main skeleton, and each type of epoxy resin is further classified as follows. Specifically, they are classified into 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-mentioned 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 resins; stilbene type epoxy resins; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resin, naphthol novolac type epoxy resin, naphthol type epoxy resin, naphthol aralkyl type epoxy resin, and naphthylene ether type epoxy resin; biphenyl type epoxy resin; biphenyl aralkyl type epoxy resin; xylylene type epoxy resin; dihydroanthracene type epoxy resin; aliphatic chain epoxy resin; and rubber-modified epoxy resins. Among these, bisphenol-based novolac type epoxy resins are preferred, and bisphenol F novolac type epoxy resins are more preferred.

The (a22) ethylenically unsaturated group-containing organic acid and the (a23) saturated group-containing or unsaturated group-containing polybasic acid anhydride are explained in the same manner as the (a2) ethylenically unsaturated group-containing organic acid and the (a3) saturated group-containing or unsaturated group-containing polybasic acid anhydride, and preferred embodiments are also the same.
In addition, as a method for reacting the compound obtained by modifying the (a21) component with the (a22) component with the (a23) component, reference can be made to a method for reacting the compound obtained by modifying the (a1) component with the (a2) component with the (a3) component.

(A2-1) As the acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton, commercially available products may be used, and 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).

When the (A) component contains both the (A1) component (or the (A1-1) component) and the (A2-1) component, from the viewpoint of a balance of properties such as via resolution, adhesive strength with plated copper, and electrical insulation reliability, the content ratio of the (A1) component (or the (A1-1) component) to the (A2-1) component [(A1) or (A1-1)/(A2-1)] is preferably 20/80 to 99/1, more preferably 50/50 to 99/1, even more preferably 60/40 to 99/1, particularly preferably 60/40 to 85/15, and most preferably 65/35 to 80/20, by mass.

((A2-2) Styrene-maleic acid resin)
As the (A) photopolymerizable compound having an ethylenically unsaturated group, a "styrene-maleic acid resin (A2-2)" such as a hydroxyethyl (meth)acrylate modified product of a styrene-maleic anhydride copolymer can also be used in combination. The (A2-2) component does not contain an alicyclic skeleton. The (A2-2) component may be used alone or in combination of two or more types.

((A2-3) Epoxy-based polyurethane resin)
In addition, as the (A) photopolymerizable compound having an ethylenically unsaturated group, an "epoxy polyurethane resin (A2-3)" obtained by reacting a compound obtained by modifying the (a21) epoxy resin with an (a22) ethylenically unsaturated group-containing organic acid (for example, component (A')) with an isocyanate compound can also be used in combination. The (A2-3) component does not contain an alicyclic skeleton. The (A2-3) component may be used alone or in combination of two or more types.

(Component (A) other than the above)
From the viewpoint of increasing the chemical resistance after curing (exposure) and increasing the difference in developer resistance between the exposed and unexposed areas, the photopolymerizable compound (A) having an ethylenically unsaturated group is preferably an embodiment that further includes at least one selected from the group consisting of (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 multifunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups, and more preferably an embodiment that includes the component (Aiii). The components (Ai) to (Aiii) preferably have a molecular weight of 1,000 or less. However, in the present invention, the components (Ai) to (Aiii) do not include the component (A).

((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) Bifunctional Vinyl Monomer)
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. As the component (Aii), one type may be used alone, or two or more types may be used in combination.

((Aiii) Multifunctional Vinyl Monomer)
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 increasing the chemical resistance after curing (exposure) and increasing the difference in developer resistance between the exposed and unexposed areas, 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.
Here, the "(meth)acrylate compound having a skeleton derived from XXX" (wherein XXX is the name of the compound) means an esterification product of XXX and (meth)acrylic acid, and the esterification product also includes a compound modified with an alkyleneoxy group.

(Content of component (A))
The content of the component (A) is not particularly limited, but from the viewpoints of 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 %, particularly preferably 25 to 50 mass %, and most preferably 30 to 45 mass %, based on the total solid content of the photosensitive resin composition.

The component (A) is not particularly limited, but from the viewpoint of photosensitive properties, it is preferable to use the component (A1) or the component (A2-1) in combination with the component (Aiii). In this case, the content ratio of the component (A1) or the component (A2-1) to the component (Aiii) [{(A1) or (A2-1)}/(Aiii)] (mass ratio) is preferably 2 to 20, more preferably 2 to 15, even more preferably 2.5 to 10, and particularly preferably 3 to 6.
Furthermore, the content ratio of the component (A1) relative to the total amount of the component (A) is preferably 20 to 95 mass%, more preferably 40 to 90 mass%, even more preferably 55 to 90 mass%, and particularly preferably 70 to 90 mass%, from the viewpoints of via resolution, adhesive strength with plated copper, electrical insulation reliability, and crack resistance.

<(B) Photopolymerization initiator>
The component (B) used in the present embodiment 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 component (B) include benzoins 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)-1-butanone, 2-methyl-1-[4-(methyl acetophenones such as [2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2-amylanthraquinone, 2-aminoanthraquinone, etc.; anthraquinones such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone, thioxanthones such as xanthones; ketals such as acetophenone dimethyl ketal and benzil dimethyl ketal; benzophenones such as benzophenone, methylbenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylamino)benzophenone, Michler's ketone and 4-benzoyl-4'-methyldiphenyl sulfide; acridines such as 9-phenylacridine and 1,7-bis(9,9'-acridinyl)heptane; 2,4,6- Examples of the oxime esters include 1,2-octanedione-1-[4-(phenylthio)phenyl]-2-(O-benzoyloxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]ethanone-1-(O-acetyloxime), and 1-phenyl-1,2-propanedione-2-[O-(ethoxycarbonyl)oxime]. Among these, acetophenones and thioxanthones are preferred, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone and 2,4-diethylthioxanthone are more preferred. Acetophenones have the advantage of being less volatile and less likely to be generated as outgassing, and thioxanthones have the advantage of being photocurable even in the visible light range.
The component (B) may be used alone or in combination of two or more. When using two or more in combination, it is preferable to use an acetophenone in combination with a thioxanthone, 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 (B))
In the photosensitive resin composition of this embodiment, the content of component (B) is not particularly limited, but is preferably 0.1 to 15 mass%, more preferably 0.15 to 5 mass%, even more preferably 0.15 to 1.5 mass%, and particularly preferably 0.20 to 0.8 mass%, based on the total solid content of the photosensitive resin composition. If the content of component (B) is 0.1 mass% or more, there is a tendency to reduce the risk of the exposed portion of the interlayer insulating layer formed using the photosensitive resin composition being eluted during development, and if it is 15 mass% or less, there is a tendency to improve heat resistance.

<(B') Photopolymerization Initiator Auxiliary Agent>
The photosensitive resin composition of the present embodiment may contain a photopolymerization initiation aid (B') together with the above-mentioned component (B). Examples of the photopolymerization initiation aid (B') include tertiary amines such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, and triethanolamine. The component (B') may be used alone or in combination of two or more.
When the photosensitive resin composition of the present embodiment contains the component (B'), the content thereof is preferably 0.01 to 20 mass %, more preferably 0.2 to 5 mass %, and even more preferably 0.3 to 2 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 (B').

<(C) Benzoxazine Compound>
The photosensitive resin composition of the present embodiment contains a benzoxazine compound (C). The component (C) may be used alone or in combination of two or more kinds.
By including the component (C), the effect of improving the adhesion to plated copper is realized. In order to improve the adhesion to plated copper, a phenolic resin or the like can be used, but in that case, the sensitivity of the photosensitive resin composition decreases, and the productivity decreases. However, the component (C) used in the present invention does not cause such problems, and while improving the adhesion to plated copper, it also has a high glass transition temperature and tends to maintain good dielectric properties.
Although the exact mechanism by which component (C) provides the above-mentioned effects is unknown, it is speculated as follows: Because component (C) has a benzoxazine ring in its molecular structure, it undergoes a ring-opening polymerization reaction when heated, forming a crosslinked structure while generating phenolic hydroxyl groups without generating volatile matter, which is thought to be what provides the above-mentioned effects.

The component (C) is not particularly limited as long as it is a compound having one or more benzoxazine rings in its molecular structure, but it preferably has one to three benzoxazine rings in its molecular structure, and more preferably has two benzoxazine rings in its molecular structure.
As the component (C), a known benzoxazine compound can be used, and examples thereof include P-d type benzoxazine compounds, F-a type benzoxazine compounds, ALP-d type benzoxazine compounds, and T-ala type benzoxazine compounds. It is considered that P-d type polybenzoxazine is crosslinked by a rigid structure and has a small free volume, and therefore has excellent thermal properties and mechanical properties. On the other hand, in polybenzoxazine having an F-a type benzoxazine structure, the aryl group becomes a steric hindrance, and it is considered that the thermal properties and mechanical properties are inferior to those of P-d type polybenzoxazine, but the steric structure gives it excellent solubility in solvents, and therefore it can be suitably used as a film material.

Examples of the component (C) include a benzoxazine compound represented by the following general formula (C-1), a benzoxazine compound represented by the following general formula (C-2), and a benzoxazine compound represented by the following general formula (C-3). The benzoxazine compound represented by the following general formula (C-1) corresponds to a P-d type benzoxazine compound, and the benzoxazine compound represented by the following general formula (C-2) corresponds to a Fa type benzoxazine compound.

(In the formula, R ^c1 and R ^c2 each independently represent a hydrocarbon group having 1 to 10 carbon atoms. X ^c1 represents a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)-, or a single bond. n ^c1 and n ^c2 each independently represent an integer of 0 to 4.)

(In the formula, each R ^c3 is independently a hydrocarbon group having 1 to 10 carbon atoms. Each R ^c4 is independently a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. Each ^{X c2} is a single bond, an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)- or a single bond. Each ^{n c3} is independently an integer of 0 to 3.)

(In the formula, R ^c5 is a hydrocarbon group having 1 to 10 carbon atoms. R ^c6 is a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. n ^c4 is an integer of 0 to 4.)

In the above general formula (C-1), examples of the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c1 and R ^c2 include aliphatic hydrocarbon groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-octyl group, and an n-decyl group; and aromatic hydrocarbon groups such as a phenyl group.
In the above general formula (C-1), n ^c1 and n ^c2 are each independently an integer of 0 to 4, and from the viewpoint of availability, an integer of 0 to 2 is preferable, and 0 is more preferable. When ^{n c1} and n ^c2 are integers of 2 or more, multiple R ^c1s and multiple R ^c2s may be the same or different.
In the above general formula (C-1), examples of the alkylene group having 1 to 5 carbon atoms represented by ^Xc1 include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. As the alkylene group, an alkylene group having 1 to 3 carbon atoms is preferable, and a methylene group is more preferable.
In the above general formula (C-1), examples of the alkylidene group having 2 to 5 carbon atoms represented by ^Xc1 include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. Among these, an isopropylidene group is preferable.

In the above general formula (C-2), examples of the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c3 include aliphatic hydrocarbon groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-octyl group, and an n-decyl group; and aromatic hydrocarbon groups such as a phenyl group.
In the above general formula (C-2), n ^c3 is an integer of 0 to 3, and from the viewpoint of availability, an integer of 0 to 2 is preferable, and 0 is more preferable.
In the above general formula (C-2), examples of the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^c2 include the same as the alkylene group having 1 to 5 carbon atoms and the alkylidene group having 2 to 5 carbon atoms represented by X ^c1 in the above general formula (C-1).
In the above general formula (C-2), examples of the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c4 include alkyl groups such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, t-butyl group, n-pentyl group, etc.; aromatic hydrocarbon groups such as phenyl group, naphthyl group, etc. Among these, aromatic hydrocarbon groups are preferred, and phenyl group is more preferred.

In the above general formula (C-3), examples of the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c5 include aliphatic hydrocarbon groups such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, an n-octyl group, and an n-decyl group; and aromatic hydrocarbon groups such as a phenyl group.
In the above general formula (C-3), n ^c4 is an integer of 0 to 4, and from the viewpoint of availability, an integer of 0 to 2 is preferable, and 0 is more preferable. When n ^c4 is an integer of 2 or more, multiple R ^c5 may be the same or different.
In the above general formula (C-3), examples of the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c6 include the same as the hydrocarbon group having 1 to 10 carbon atoms represented by R ^c4 in the above general formula (C-2).

Among the benzoxazine compounds represented by any of the above general formulas (C-1) to (C-3), from the viewpoint of heat resistance, the benzoxazine compound represented by the above general formula (C-1) and the benzoxazine compound represented by the above general formula (C-2) are preferred, and the benzoxazine compound represented by the above general formula (C-1) is more preferred.
From the viewpoint of adhesion to copper plating, the benzoxazine compound represented by the above general formula (C-1) is preferably a benzoxazine compound represented by the following formula (C-4), and the benzoxazine compound represented by the above general formula (C-2) is preferably a benzoxazine compound represented by the following formula (C-5).

(C) Method for Producing Benzoxazine Compounds)
The method for producing the component (C) is not particularly limited, and a known method can be used. For example, the benzoxazine compound (C) can be produced by the reaction of (c1) a compound having a phenolic hydroxyl group with a hydrogen atom bonded to at least one of the ortho positions [hereinafter, sometimes abbreviated as compound (c1) having a phenolic hydroxyl group], (c2) a primary amine [hereinafter, referred to as primary amine (c2)], and (c3) formaldehyde [hereinafter, referred to as formaldehyde (c3)].
For example, when the compound (c1) having a phenolic hydroxyl group is phenol and the primary amine (c2) is aniline, the above reaction is represented by the following reaction formula (1).

Examples of the compound (c1) having a phenolic hydroxyl group, which is one of the raw materials, include phenols, polyfunctional phenols, biphenol compounds, bisphenols, trisphenols, tetraphenols, phenol resins, and the like. Among these, phenols are preferred, and phenol is more preferred. Examples of phenols include phenol, 2-methylphenol, 4-methylphenol, 2-ethylphenol, 3-methyl-4-isopropylphenol, and the like. The compound (c1) having a phenolic hydroxyl group may be used alone or in combination of two or more types, but it is usually preferred to use one type alone.

Primary amines (c2), which are one of the raw materials, include, for example, aliphatic amines such as methylamine, butylamine, and cyclohexylamine; and aromatic amines such as aniline, substituted anilines, toluidine, and anisidine. Among these, aromatic amines are preferred, aniline and substituted anilines are more preferred, and aniline is even more preferred. Examples of substituted anilines include 2-methoxyaniline and 4-methoxyaniline. Primary amines (c2) may be used alone or in combination of two or more types, but it is usually preferred to use one type alone.

Formaldehyde (c3), one of the raw materials, can be formalin (aqueous formaldehyde solution) or paraformaldehyde, which is a solid.

When producing component (C), there is no particular restriction on the amount of each of the raw materials used, but it is preferable to use 0.5 to 1 mole of primary amine (c2) per mole of phenolic hydroxyl group in compound (c1) having a phenolic hydroxyl group, and 2 moles or more of formaldehyde (c3) per mole of primary amine (c2). By using the amount of primary amine (c2) as described above, some of the phenolic hydroxyl groups in compound (c1) having a phenolic hydroxyl group tend to remain unreacted, which tends to improve adhesion and glass transition temperature.

The manufacturing conditions for component (C) can be any known conditions. Specifically, a mixture of compound (c1) having a phenolic hydroxyl group and primary amine (c2) is added to formaldehyde (c3) that has been heated to preferably 70°C or higher (more preferably 70 to 110°C), and reacted at preferably 70 to 110°C (more preferably 90 to 100°C) for preferably 20 minutes to 8 hours (more preferably 20 minutes to 2 hours), and then dried under reduced pressure at 120°C or lower to obtain component (C).

After the reaction is completed, the product is separated by a method generally used in organic synthetic chemistry, such as extraction, and volatile components such as condensation water are removed by drying, thereby obtaining the benzoxazine compound (C).
By utilizing or applying the above-mentioned production methods, benzoxazine compounds (C) having various structures can be obtained.
As the benzoxazine compound (C), commercially available products can also be used, such as "Pd-type benzoxazine" and "Fa-type benzoxazine" manufactured by Shikoku Chemical Industry Co., Ltd., benzoxazine resin manufactured by Konishi Chemical Industry Co., Ltd., and cashew benzoxazine resin manufactured by Tohoku Kako Co., Ltd.

(Content of component (C))
In the photosensitive resin composition of this embodiment, the content of component (C) is not particularly limited, but is preferably 0.5 to 30 mass%, more preferably 0.8 to 25 mass%, even more preferably 1 to 20 mass%, particularly preferably 1 to 18 mass%, and most preferably 1 to 5 mass%, based on the total solid content of the photosensitive resin composition. If the content of component (C) is 0.5 mass% or more, the adhesive strength with plated copper and the electrical insulation reliability are improved with low density. On the other hand, if it is 30 mass% or less, the resolution is good.

<(D) Thermosetting resin>
The photosensitive resin composition of the present embodiment may further contain, and preferably contains, a thermosetting resin as component (D). Component (D) does not include anything that corresponds to component (A), and in that respect, component (D) can be said to have no ethylenically unsaturated groups.
By including the thermosetting resin (D) in the photosensitive resin composition of the present embodiment, the adhesive strength with plated copper and the insulation reliability are improved, and the heat resistance is also likely to be improved. This is presumably because, in addition to the formation of a crosslinked structure by the thermosetting resin (D), a crosslinked structure is formed between the phenolic hydroxyl group generated by heating the benzoxazine compound (C) and the thermosetting resin (D).

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, silicone resin, triazine resin, melamine resin, etc. Also, the thermosetting resin is not particularly limited to these, and any known thermosetting resin can be used. Among these, epoxy resin is preferable.
The component (D) may be used alone or in combination of two or more types.

The 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.

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; stilbene-type epoxy resins; and naphthalene-type epoxy resins. Epoxy resins that contain a naphthalene skeleton, such as 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; alicyclic epoxy resins, such as dicyclopentadiene type epoxy resins; heterocyclic epoxy resins; spiro ring-containing epoxy resins; cyclohexane dimethanol type epoxy resins; trimethylol type epoxy resins; aliphatic linear epoxy resins; and rubber-modified epoxy resins.
The component (D) may be used alone or in combination of two or more types.

Among these, particularly from the viewpoints of heat resistance, electrical insulation reliability, and adhesive strength with plated copper, bisphenol-based epoxy resins, naphthol-type epoxy resins, naphthalene-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, and cresol novolac-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 particularly preferred.
These may be commercially available products, and examples of such products include bisphenol A type epoxy resins ("jER828EL" and "YL980" manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins ("jER806H" and "YL983U" manufactured by Mitsubishi Chemical Corporation), naphthalene type epoxy resins ("HP4032D" and "HP4710" manufactured by DIC Corporation), naphthalene skeleton-containing multifunctional epoxy resins ("NC7000" manufactured by Nippon Kayaku Co., Ltd.), naphthol type epoxy resins ("ESN-47" manufactured by Nippon Steel Chemical & Material Co., Ltd.), and the like. 5V"), epoxy resins having a biphenyl structure ("NC3000H" and "NC3500" manufactured by Nippon Kayaku Co., Ltd.), Mitsubishi Chemical Corporation ("YX4000HK" and "YL6121"), anthracene type epoxy resins ("YX8800" manufactured by Mitsubishi Chemical Corporation), glycerol type epoxy resins ("ZX1542" manufactured by Nippon Steel Chemical & Material Co., Ltd.), naphthylene ether type epoxy resins ("EXA7311-G4" manufactured by DIC Corporation), and cresol novolac type epoxy resins ("EPICLON N-680" manufactured by DIC Corporation).

(Content of component (D))
In the photosensitive resin composition of this embodiment, the content of the 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 8 to 20 mass %, based on the total solid content of the photosensitive resin composition. If the content of the component (D) is 5 mass % or more, sufficient crosslinking of the photosensitive resin composition is obtained, and the adhesive strength with plated copper and the electrical insulation reliability tend to be improved. On the other hand, if it is 70 mass % or less, the resolution of the vias tends to be good.

<(E) Elastomer>
The photosensitive resin composition of the present embodiment may contain, and preferably contains, an elastomer as component (E). By containing component (E), the photosensitive resin composition tends to have excellent via resolution, adhesive strength with plated copper, and electrical insulation reliability. In addition, component (E) has the effect of suppressing a decrease in flexibility and adhesive strength with plated copper caused by distortion (internal stress) inside the cured product due to the cure shrinkage of component (A).
As component (E), an elastomer that is liquid at 25°C is preferred.
The component (E) may be used alone or in combination of two or more types.

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, the former of which tends to contribute to heat resistance and strength, and the latter of which tends to contribute to flexibility and toughness.
Among the above-mentioned examples, component (E) preferably contains at least one selected from the group consisting of olefin-based elastomers, polyester-based elastomers, and urethane-based elastomers, more preferably contains a polyester-based elastomer, and further preferably contains at least one selected from the group consisting of olefin-based elastomers, polyester-based elastomers, and urethane-based elastomers, and particularly preferably contains a polyester-based elastomer, from the viewpoints of compatibility, solubility, and adhesive strength with plated copper.

(Polyester elastomer)
The polyester elastomer may be one obtained by polycondensation of a dicarboxylic acid or a derivative thereof and a diol compound or a derivative thereof. The polyester elastomer may be used alone or in combination of two or more kinds.
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 in the aromatic rings of the aromatic dicarboxylic acids are substituted with methyl groups, ethyl groups, phenyl groups, and the like; 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 adhesion to the substrate. The dicarboxylic acid may be used alone or in combination of two or more kinds.
Examples of the derivatives of the dicarboxylic acids include anhydrides of the dicarboxylic acids.

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; and aromatic diols represented by the following general formula (E-1). The diol compounds may be used alone or in combination of two or more.

(In general formula (E-1), X ^E1 represents an alkylene group having 1 to 10 carbon atoms, an alkylidene group having 2 to 10 carbon atoms, a cycloalkylene group having 4 to 8 carbon atoms, -O-, -S-, or -SO ₂ -. ^{R E1} and R ^E2 each independently represent a halogen atom or an alkyl group having 1 to 12 carbon atoms. p and q each independently represent an integer of 0 to 4, and r is 0 or 1.)

In general formula (E-1), examples of the alkylene group having 1 to 10 carbon atoms represented by X ^E1 include a methylene group, a 1,2-dimethylene group, a 1,3-trimethylene group, a 1,4-tetramethylene group, a 1,5-pentamethylene group, etc. From the viewpoints of via resolution, adhesive strength with plated copper, and electrical insulation reliability, the alkylene group is preferably an alkylene group having 1 to 3 carbon atoms, and more preferably a methylene group.
Examples of the alkylidene group having 2 to 10 carbon atoms represented by ^XE1 include an ethylidene group, a propylidene group, an isopropylidene group, a butylidene group, an isobutylidene group, a pentylidene group, an isopentylidene group, etc. As the alkylidene group, an isopropylidene group is preferred from the viewpoints of via resolution, adhesive strength with plated copper, and electrical insulation reliability.
Examples of the cycloalkylene group having 4 to 8 carbon atoms represented by ^XE1 include a cyclopentylene group, a cyclohexylene group, and a cyclooctylene group.
Among the above, ^XE1 is preferably an alkylene group having 1 to 10 carbon atoms or an alkylidene group having 2 to 10 carbon atoms, more preferably a methylene group or an isopropylidene group.

In formula (E-1), examples of the halogen atom represented by R ^E1 and R ^E2 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the alkyl group having 1 to 12 carbon atoms represented by R ^E1 and R ^E2 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, an n-pentyl group, etc. As the alkyl group, an alkyl group having 1 to 6 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is further preferable.
p and q each independently represent an integer of 0 to 4, and are each preferably 0 or 1.
The subscript r may be either 0 or 1, but when r is 0, the structure is represented by the following general formula (D-1').

(In formula (E-1'), X ^E1 , R ^E1 and p are all the same as those in formula (E-1), and the preferred embodiments are also the same.)

Examples of aromatic diols represented by the general formula (E-1) include bisphenol A, bis(4-hydroxyphenyl)methane, bis(4-hydroxy-3-methylphenyl)propane, and resorcinol.

Furthermore, as the polyester-based elastomer, a multiblock copolymer in which an aromatic polyester (e.g., polybutylene terephthalate) portion is the hard segment component and an aliphatic polyester (e.g., polytetramethylene glycol) portion is the soft segment component can also be used, and it is preferable to use such a multiblock copolymer. As such multiblock copolymers, there are various grades of commercially available products that differ in the type, ratio, and molecular weight of the hard and soft segments. Specific examples include "Hytrel (registered trademark)" (manufactured by DuPont-Toray Co., Ltd.), "Pelprene (registered trademark)" (manufactured by Toyobo Co., Ltd.), "Espel (registered trademark)" and "Teslac (registered trademark)" (manufactured by Hitachi Chemical Co., Ltd.), etc.

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 20,000.

(Other elastomers)
In addition, the component (E) may be 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, tetrafluoroethylene resin, polyacrylonitrile resin, maleic anhydride-modified polybutadiene, phenol-modified polybutadiene, and carboxy-modified polyacrylonitrile.

(Content of component (E))
When the photosensitive resin composition of the present embodiment contains the component (E), the content thereof is preferably 0.5 to 20 mass%, more preferably 0.5 to 15 mass%, even more preferably 0.5 to 10 mass%, particularly preferably 1.0 to 6 mass%, and most preferably 1.3 to 4.0 mass%, based on the total solid content of the photosensitive resin composition. If the content of the component (E) is 0.5 mass% or more, the effect of improving the adhesive strength with plated copper becomes sufficient, and the electrical insulation reliability tends to be even more excellent. If the content of the component (E) is 20 mass% or less, the resolution of the via, the adhesive strength with plated copper, and the electrical insulation reliability all tend to be sufficient.

(Content of component (E))
When the photosensitive resin composition of the present embodiment contains the component (E), its content is not particularly limited, but is preferably 0.01 to 5 mass%, more preferably 0.02 to 3 mass%, and even more preferably 0.03 to 2 mass%, based on the total amount of the resin components of the photosensitive resin composition. If it is 0.01 mass% or more, sufficient heat curing tends to be achieved, and if it is 5 mass% or less, the photosensitive characteristics and heat resistance tend to be good.

<(F) Inorganic filler>
The photosensitive resin composition of the present embodiment may contain an inorganic filler as the component (F), and preferably contains an inorganic filler. By containing an inorganic filler, the thermal expansion can be reduced, and the risk of warping is reduced. In the thermosetting resin composition that has been conventionally used as an interlayer insulating layer of a multilayer printed wiring board, the thermal expansion has been reduced 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 the present embodiment tends to maintain high via resolution even if a large amount of inorganic filler is contained. Therefore, with the photosensitive resin composition of the present embodiment, it is possible to achieve both low thermal expansion and high via resolution.

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, etc. As _the (F) component, one type may be used alone, or two or more types may be used in combination.

From the viewpoints of heat resistance and low thermal expansion, it is preferable that component (F) contains silica, and it is more preferable that it is silica. In addition, component (F) may be surface-treated with alumina or an organosilane compound from the viewpoint of improving the dispersibility of the inorganic filler in the photosensitive resin composition by preventing aggregation.

From the viewpoint of via resolution, the average particle diameter of the (F) component is preferably 0.01 to 5 μm, more preferably 0.1 to 3 μm, even more preferably 0.1 to 2 μm, and particularly preferably 0.1 to 1 μm. Here, the average particle diameter of the (F) component is the volume average particle diameter of the inorganic filler in a state dispersed in the photosensitive resin composition, and is the 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 at a refractive index of 1.38 using a submicron particle analyzer (manufactured by Beckman Coulter, Inc., product name: N5) in accordance with the international standard ISO13321, and the particle diameter at an integrated value of 50% (volume basis) in the particle size distribution is taken as the average particle diameter (volume average particle diameter). In addition, the (F) component contained in the photosensitive resin film and interlayer insulating layer provided on the carrier film can also be measured using the submicron particle analyzer after diluting (or dissolving) it 1,000 times (volume ratio) using a solvent as described above.

(Content of component (F))
When the photosensitive resin composition of the present embodiment contains the component (F), its content is not particularly limited, but is preferably 5 to 80 mass %, more preferably 15 to 60 mass %, still more preferably 15 to 55 mass %, particularly preferably 20 to 50 mass %, and most preferably 30 to 45 mass %, based on the total solid content of the photosensitive resin composition. If the content of the component (F) is within the above range, the mechanical strength, heat resistance, via resolution, and the like can be improved.

<(G) Pigment>
The photosensitive resin composition of the present embodiment may contain a pigment as component (G) according to a desired color in order to adjust photosensitivity, etc. As the component (G), a colorant that develops a 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, carbon black, and naphthalene black.

(Content of component (G))
When the photosensitive resin composition of the present embodiment contains the component (G), 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 viewpoint of adjusting photosensitivity, etc.

<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, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers 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; esters such as ethyl acetate, butyl acetate, propylene glycol monoethyl ether acetate, butyl cellosolve acetate, and carbitol acetate; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha. The diluent may be used alone or in combination of two or more. As the diluent, ketones and esters are preferable, and esters are more preferable.

(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 40 to 90 mass%, more preferably 50 to 80 mass%, and even more preferably 55 to 70 mass%. By adjusting the amount of the diluent used in this manner, the coatability of the photosensitive resin composition is improved, and a more precise pattern can be formed.

<Other ingredients>
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, foam stabilizers such as silicone foam stabilizers, fluorine foam stabilizers, and vinyl resin foam stabilizers, and silane coupling agents, as required.Furthermore, the composition may contain flame retardants such as brominated epoxy compounds, acid-modified brominated epoxy compounds, phosphate compounds of antimony compounds and phosphorus compounds, aromatic condensed phosphate esters, and halogen-containing condensed phosphate esters, thermoplastic resins such as polyester polyurethane resins, and the like.

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, photosensitive resin film for interlayer insulating layer]
The photosensitive resin film of the present embodiment is a photosensitive layer that will later become an interlayer insulating layer, and is made of the photosensitive resin composition of the present embodiment. The photosensitive resin film of the present 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 polyester films such as polyethylene terephthalate film and polybutylene terephthalate film, and polyolefin films such as polypropylene film and polyethylene film. The thickness of the carrier film may be appropriately selected from the range of 5 to 100 μm, but is preferably 5 to 60 μm, and 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 preventing the diluent from diffusing during the manufacturing process of the multilayer printed wiring board.

The photosensitive resin film of this embodiment has excellent via resolution, adhesive strength with plated copper, electrical insulation reliability, and crack resistance, and is therefore suitable as an interlayer insulating layer for a multilayer printed wiring board. In other words, the present invention also provides a photosensitive resin film for an interlayer insulating layer. The photosensitive resin film for an interlayer insulating layer can also be called an interlayer insulating photosensitive film.

[Multilayer printed wiring board and its manufacturing method]
The present invention also provides a multilayer printed wiring board containing an interlayer insulating layer formed using the photosensitive resin composition or photosensitive resin film of the present embodiment. 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.

Hereinafter, as an example of a preferred embodiment of the method for producing a multilayer printed wiring board, a method for producing a multilayer printed wiring board using the photosensitive resin film of this embodiment (photosensitive resin film for interlayer insulating layer) 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 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 referred to as "photovia forming step (2)").
Step (3): A step of roughening the vias and the interlayer insulating layer (hereinafter referred to as "roughening step (3)").
Step (4): A step of forming a circuit pattern on the interlayer insulating layer (hereinafter 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 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 mJ/cm ² , and more preferably 15 to 500 mJ/cm 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 the present embodiment.
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 paddle method, a spray method, brushing, slapping, scraping, and swing immersion. Among these, from the viewpoint of improving the resolution of the via, 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 is 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 60 μm or less, and can also be less than 40 μm 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 necessarily limited to 60 μm or less, and may be, for example, about 200 μm or less, and can also be arbitrarily selected, for example, in the range of 15 to 300 μm.

(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 forming 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, the circuit pattern is preferably formed by a semi-additive process, which not only forms the circuit pattern but also provides electrical continuity through the vias.
In the semi-additive process, first, the via bottom, via wall surface, and the entire surface of the interlayer insulating layer after the roughening treatment step (3) are subjected to electroless copper plating treatment using a palladium catalyst or the like to form a seed layer 105. The seed layer is for forming 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 in thickness, there is a tendency 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 wirings, 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 Co., Ltd. and "ThruCup (registered trademark) PEA ver. 4" series 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 electrical insulation reliability, curing characteristics, and adhesive strength with plated copper. The heat-curing 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 entire process of manufacturing a printed wiring board using the photovia method, but this process is repeated to manufacture a board depending on the number of interlayer insulating layers required. Then, a solder resist layer 108 is preferably formed as the outermost layer.

The method for producing a multilayer printed wiring board in which vias are formed using the photosensitive resin composition of this embodiment has been described above, but since the photosensitive resin composition of this embodiment has excellent pattern resolution, it is also suitable for forming cavities for incorporating chips, passive elements, etc. The cavities can be suitably formed, for example, by selecting a drawing pattern that can form a desired cavity when forming a pattern by exposing the photosensitive resin film in the above description of the multilayer printed wiring board.
Furthermore, the photosensitive resin composition of the present embodiment is also useful as a surface protective film for solder resist and the like.

[Semiconductor Package]
The present invention also provides a semiconductor package comprising a semiconductor element mounted on the multilayer printed wiring board of the present embodiment. The semiconductor package of the present embodiment can be manufactured by mounting a semiconductor element such as a semiconductor chip or memory at a predetermined position on the multilayer printed wiring board of the present invention 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 each example were evaluated by the methods described below.

[1. Evaluation of via resolution]
(1-1) Preparation of Laminate for Evaluation The copper foil surface of a substrate for printed wiring boards (manufactured by Hitachi Chemical Co., Ltd., product name "MCL-E-679") in which a copper foil with a thickness of 12 μm was laminated on a glass epoxy base material was treated with a roughening treatment solution (manufactured by MEC Co., Ltd., product name "CZ-8100"), followed by rinsing with water and drying to obtain a roughening-treated substrate for printed wiring boards.
Next, the protective film was peeled off and removed from the "photosensitive resin film with the carrier film and the protective film laminated thereto" 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 printed wiring board substrate that had been roughened. A press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500") was used to perform lamination. The lamination conditions were a press hot plate temperature of 70°C, a vacuuming time of 20 seconds, a lamination press time of 30 seconds, an atmospheric pressure of 4 kPa or less, and a pressure of 0.4 MPa. After lamination, the product was left at room temperature for 1 hour or more to obtain an evaluation laminate in which the photosensitive resin film and the carrier film were laminated in this order on the copper foil surface of the printed wiring board substrate.
(1-2) Sensitivity Measurement of Photosensitive Resin Film After peeling and removing the carrier film of the evaluation laminate obtained in (1-1) above, a 41-step 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 were arranged in a lattice (dot diameter: distance between dot centers = 1:2). The dot diameter (φ) was changed in 5 μm increments in the range of 30 to 200 μm.
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 8.0 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.
(1-3) Evaluation of via resolution The via resolution was evaluated by exposing the photosensitive resin film to an exposure energy amount that gave a sensitivity of 8.0 steps, i.e., the number of steps, measured in (1-2) above, and then spray developing the film. The via pattern was observed using an optical microscope and evaluated according to the following criteria. The above-mentioned "opening" state refers to a state in which the copper foil of the printed wiring board substrate can be confirmed when the via portion of the dot pattern is observed using an optical microscope. A rating of "A" indicates good characteristics.
A: The φ60 μm via portion of the dot pattern is open.
B: The φ200 μm via portion of the dot pattern is open.
C: The φ200 μm via portion of the dot pattern is not opened.

[2. Evaluation of adhesive strength (peel strength) with plated copper]
While peeling off the protective film from the "photosensitive resin film having a carrier film and a protective film laminated thereto" produced in each of the Examples and Comparative Examples, lamination was performed on a copper-clad laminate substrate having a thickness of 1.0 mm using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500") at a pressure of 0.4 MPa, a press hot plate temperature of 80°C, a vacuum drawing time of 25 seconds, a lamination press time of 25 seconds, and an air pressure of 4 kPa or less to obtain a laminate.
The obtained laminate was exposed to light at 500 mJ/ ^cm2 using a parallel light exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201") with an ultra-high pressure mercury lamp as the light source. Next, the laminate was exposed to light at an exposure dose of 2,000 mJ/ ^cm2 using an ultraviolet exposure device and heated at 170°C for 1 hour to obtain a laminate for evaluation in which a cured product (cured film) was formed on the copper-clad laminate substrate.

Next, first, an aqueous solution of diethylene glycol monobutyl ether: 200 ml/L and sodium hydroxide: 5 g/L was prepared as a swelling liquid, and the evaluation laminate was immersed for 10 minutes while being heated to 60° C. Next, an aqueous solution of potassium permanganate: 60 g/L and sodium hydroxide: 40 g/L was prepared as a roughening liquid, and the evaluation laminate was immersed for 10 minutes while being heated to 60° C. Subsequently, an aqueous solution of neutralizing liquid (tin chloride (SnCl ₂ ): 30 g/L, hydrogen chloride: 300 ml/L) was prepared, and the evaluation laminate was immersed for 5 minutes while being heated to 40° C., to reduce potassium permanganate. In this manner, the surface of the cured evaluation laminate was desmeared.
Next, the surface of the cured product of the desmeared evaluation laminate was treated with an alkaline cleaner "Cleaner Securiganth 902" (product name, manufactured by Atotech Japan Co., Ltd.) at 60°C for 5 minutes to degrease and clean. After cleaning, the desmeared cured product was treated with a pre-dip liquid "Pre-dip Neogant B" (product name, manufactured by Atotech Japan Co., Ltd.) at 23°C for 1 minute. Thereafter, the cured product was treated with an activator liquid "Activator Neogant 834" (product name, manufactured by Atotech Japan Co., Ltd.) at 35°C for 5 minutes, and then treated with a reducing liquid "Reducer Neogant WA" (product name, manufactured by Atotech Japan Co., Ltd.) at 30°C for 5 minutes.
The laminate for evaluation thus obtained was placed in a chemical copper solution ("Basic Printganth MSK-DK", "Copper Printganth MSK", "Stabilizer Printganth MSK" (all product names manufactured by Atotech Japan K.K.)) and electroless plating was carried out until the plating thickness reached approximately 0.5 μm. After the electroless plating, an annealing treatment was carried out at a temperature of 120° C. for 30 minutes in order to remove residual hydrogen gas. Thereafter, copper sulfate electrolytic plating was carried out, and an annealing treatment was carried out at 180° C. for 60 minutes to form a conductor layer with a thickness of 25 μm.

The laminate for evaluation having the conductor layer formed thereon as described above was measured for perpendicular peel strength at 23° C. in accordance with JIS C6481 (1996). Evaluation was also made according to the following evaluation criteria.
A: The adhesive strength with plated copper was 0.40 kN/m or more.
B: The adhesive strength with plated copper was 0.20 kN/m or more and less than 0.40 kN/m.
C: The adhesive strength to plated copper was less than 0.20 kN/m.

[3. Measurement of surface roughness (Ra) after roughening treatment]
The laminate having the conductor layer formed thereon, which was prepared in the above [2. Evaluation of adhesive strength (peel strength) with plated copper], was immersed in a 10% by mass aqueous solution of ammonium persulfate to remove the formed conductor layer.
The surface roughness (Ra) of the insulating layer was measured using a non-contact surface roughness meter (WYKO NT3300 manufactured by B-CO Instruments) in VSI contact mode with a 50x lens to obtain a measurement range of 121 μm×92 μm. The arithmetic mean roughness after roughening treatment was calculated from the value obtained. The average value of 10 points was taken as the measured value. Evaluation was also performed according to the following evaluation criteria.
A: Ra after the roughening treatment was less than 200 nm.
B: Ra after the roughening treatment was 200 nm or more and less than 500 nm.
C: Ra after the roughening treatment was 500 nm or more.

[4. Evaluation of HAST resistance (electrical insulation reliability after moisture absorption)]
The same operation as in the above [2. Evaluation of adhesive strength (peel strength) with plated copper] was carried out, except that a conductor layer having a thickness of 35 μm was formed instead of a conductor layer having a thickness of 25 μm, to obtain a laminate having a conductor layer formed thereon.
The formed conductor layer was etched to form a circular electrode having a diameter (φ) of 6 mm. A photosensitive solder resist film "FZ-2700GA" (manufactured by Hitachi Chemical Co., Ltd., product name) was then formed on the electrode and the cured film to a layer thickness of 25 μm using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500") at a pressure of 0.4 MPa, a press hot plate temperature of 80° C., a vacuuming time of 25 seconds, a lamination press time of 40 seconds, and an atmospheric pressure of 4 kPa or less to obtain a laminate for evaluation.

The evaluation laminate obtained as described above was exposed to light at 500 mJ/ ^cm2 over the entire surface using a parallel light exposure machine (manufactured by ORC Manufacturing Co., Ltd., product name "EXM-1201") using an ultra-high pressure mercury lamp as a light source. Next, the laminate was exposed to light at an exposure dose of 2,000 mJ/ ^cm2 using an ultraviolet exposure device, and heated at 160°C for 1 hour to obtain a cured film.
Next, wiring was performed so that the circular electrode was the positive electrode and the copper foil on the side of the copper-clad laminate on which the circular electrode was formed was the negative electrode, and the result was exposed for 200 hours under conditions of 135° C., 85%, and 5.5 V using a pressure cooker (model name: Unsaturated Type Ultra-Accelerated Life Tester PC-422RP, manufactured by Hirayama Seisakusho Co., Ltd.). The resistance value between the electrodes was measured and evaluated according to the following evaluation criteria.
A: The resistance value after 200 hours was 10×10 ⁷ Ω or more.
B: The resistance value after 200 hours was 10×10 ⁶ Ω or more and less than 10×10 ⁷ Ω.
C: The resistance value after 200 hours was less than 10×10 ⁶ Ω.

Synthesis Example 1 Synthesis of Acid-Modified Ethylenically Unsaturated Group and Alicyclic Skeleton-Containing Epoxy Derivative 1 [Component (A1-1)] 350 parts by mass of a dicyclopentadiene type epoxy resin ("XD-1000" manufactured by Nippon Kayaku Co., Ltd., epoxy equivalent 252 g/eq, softening point 74.2°C, corresponding to component (a1) and represented by the above general formula (a1-1); number of ring-forming carbon atoms in the alicyclic skeleton: 10), 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, thereby dissolving the mixture.
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 dicyclopentadiene-type epoxy acrylate having a solid content of 73% by mass (corresponding to component (A1-1) hereinafter referred to as "acid-modified ethylenically unsaturated group and alicyclic skeleton-containing epoxy derivative 1").

Synthesis Example 2 Synthesis of Acid-Modified Ethylenically Unsaturated Group and Alicyclic Skeleton-Containing Epoxy Derivative 2 [Component (A1-1)] 350 parts by mass of a dicyclopentadiene-type epoxy resin (EPICLON (registered trademark) HP-7200 manufactured by DIC Corporation, epoxy equivalent 254 to 264 g/eq, softening point 56 to 66° C., corresponding to component (a1) and represented by the above general formula (a1-1); number of ring-forming carbon atoms in the alicyclic skeleton: 10), 70 parts by mass of acrylic acid (corresponding to component (a2)), 0.5 part by mass of methylhydroquinone, and 120 parts by mass of carbitol acetate were charged and reacted by heating to 90° C. and stirring to dissolve the mixture.
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 dicyclopentadiene-type epoxy acrylate having a solid content of 74% by mass (corresponding to component (A1-1) hereinafter referred to as “acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative 2”).

Synthesis Example 3 (A2-1) Synthesis of acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton 350 parts by mass of bisphenol F novolak epoxy resin ("EXA-7376" manufactured by DIC Corporation, corresponding to component (a21)), 70 parts by mass of acrylic acid (corresponding to component (a22)), 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 to dissolve the mixture.
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 (a23)) 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 bisphenol F type epoxy acrylate having a solid content of 73% by mass (corresponding to component (A2-1) hereinafter referred to as "acid-modified ethylenically unsaturated group-containing epoxy derivative 3 not containing an alicyclic skeleton").

<Examples 1 to 8 and Comparative Examples 1 to 4>
(Preparation of Photosensitive Resin Composition)
Photosensitive resin compositions were prepared by mixing the compositions according to the formulations and amounts 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 with a solid content of 60% by mass was obtained.
(Preparation of Photosensitive Resin Film)
A 25 μm thick polyethylene terephthalate film (G2-25, 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 evaluations according to the above-mentioned methods. The results are shown in Table 1.

The components used in each example are as follows:
Component (A):
Acid-modified ethylenically unsaturated group and alicyclic skeleton-containing epoxy derivative 1 [component (A1-1)]: the one obtained in Synthesis Example 1 was used.
Acid-modified ethylenically unsaturated group and alicyclic skeleton-containing epoxy derivative 2 [component (A1-1)]: the one obtained in Synthesis Example 2 was used.
Acid-modified ethylenically unsaturated group-containing epoxy derivative 3 not containing an alicyclic skeleton [component (A2-1)]: the one obtained in Synthesis Example 3 was used.
Dipentaerythritol pentaacrylate [Component (Aiii)]
(B) component;
Photopolymerization initiator 1: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, acetophenones Photopolymerization initiator 2: 2,4-diethylthioxanthone, thioxanthones (C) component;
Benzoxazine resin "P-d type benzoxazine" (manufactured by Shikoku Chemical Industry Co., Ltd., product name)
Benzoxazine resin "F-a type benzoxazine" (product name, manufactured by Shikoku Chemical Industry Co., Ltd.)
Component (D);
Biphenyl type epoxy resin: "YX-4000" (product name, manufactured by Mitsubishi Chemical Corporation)
Component (E);
Polyester elastomer: "Espel (registered trademark) 1108" (product name, manufactured by Hitachi Chemical Co., Ltd.)
Component (F);
Silica: "SFP-20M" (manufactured by Denka Co., Ltd., average particle size 0.3 μm, product name)

As can be seen from Table 1, in Examples 1 to 8, the via resolution was excellent, the adhesive strength to the plated copper was high despite the low roughness, and the electrical insulation reliability was excellent. Furthermore, since the surface roughness Ra of the interlayer insulating layer made of the photosensitive resin composition was small, it was possible to form a fine surface shape on the surface of the interlayer insulating layer, and there is a tendency for fine wiring to be easily formed.
On the other hand, in Comparative Examples 1 to 3, which did not contain component (C), the adhesive strength with plated copper at low roughness was insufficient, and in Comparative Example 4, which contained component (C) but not component (D), the adhesive strength with plated copper at low roughness was insufficient and the electrical insulation reliability was significantly reduced.

100A Multilayer printed wiring board 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 (19)

A photosensitive resin composition comprising: (A) a photopolymerizable compound having an ethylenically unsaturated group and not containing a urethane bond ; (B) a photopolymerization initiator; (C) a benzoxazine compound; and (D) a thermosetting resin,
The photosensitive resin composition according to claim 1, wherein the (A) photopolymerizable compound having an ethylenically unsaturated group and no urethane bond comprises (A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton, and no urethane bond, and the (A1) component is (A1-1) an acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative obtained by reacting (a1) an alicyclic skeleton-containing epoxy resin modified with (a2) an ethylenically unsaturated group-containing organic acid with (a3) a saturated group- or unsaturated group-containing polybasic acid anhydride . The photosensitive resin composition according to claim 1, wherein the (C) benzoxazine compound has 1 to 3 benzoxazine rings in its molecular structure. The photosensitive resin composition according to claim 1 or 2, wherein the (C) benzoxazine compound is a benzoxazine compound represented by any one of the following general formulas (C-1) to (C-3):

(In the formula, R ^c1 and R ^c2 each independently represent a hydrocarbon group having 1 to 10 carbon atoms. X ^c1 represents an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)-, or a single bond. ^{n c1} and n ^c2 each independently represent an integer of 0 to 4.)

(In the formula, each R ^c3 is independently a hydrocarbon group having 1 to 10 carbon atoms. Each R ^c4 is independently a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. Each X ^c2 is an alkylene group having 1 to 5 carbon atoms, an alkylidene group having 2 to 5 carbon atoms, -O-, a sulfonyl group, a carbonyloxy group, -C(=O)- or a single bond. Each ^{n c3} is independently an integer of 0 to 3.)

(In the formula, R ^c5 is a hydrocarbon group having 1 to 10 carbon atoms. R ^c6 is a hydrocarbon group having 1 to 10 carbon atoms or a hydrogen atom. n ^c4 is an integer of 0 to 4.) The photosensitive resin composition according to any one of claims 1 to 3, wherein the content of the benzoxazine compound (C) is 0.5 to 30 mass% based on the total solid content of the photosensitive resin composition. The photosensitive resin composition according to any one of claims 1 to 4, wherein in the photopolymerizable compound (A1) which has an acidic substituent and an alicyclic skeleton together with an ethylenically unsaturated group, and does not contain a urethane bond , the alicyclic skeleton is an alicyclic skeleton having 5 to 20 ring carbon atoms. The photosensitive resin composition according to any one of claims 1 to 5, wherein in the photopolymerizable compound (A1) which has an acidic substituent and an alicyclic skeleton together with an ethylenically unsaturated group, and does not contain a urethane bond , the alicyclic skeleton has two or more rings. The photosensitive resin composition according to any one of claims 1 to 6, wherein the photopolymerizable compound (A) having an ethylenically unsaturated group and not containing a urethane bond further comprises at least one selected from the group consisting of (Ai) a monofunctional vinyl monomer having one polymerizable ethylenically unsaturated group, (Aii) a difunctional vinyl monomer having two polymerizable ethylenically unsaturated groups, and (Aiii) a polyfunctional vinyl monomer having at least three polymerizable ethylenically unsaturated groups. The photosensitive resin composition according to any one of claims 1 to 7, wherein the (D) thermosetting resin is at least one selected from the group consisting of an epoxy resin , a phenolic resin, an unsaturated imide resin, a cyanate resin, an isocyanate resin, an oxetane resin, an amino resin, an unsaturated polyester resin, an allyl resin, a dicyclopentadiene resin, a silicone resin, a triazine resin, and a melamine resin. The photosensitive resin composition according to any one of claims 1 to 8, further comprising (E) an elastomer. The photosensitive resin composition according to claim 9, wherein the (E) elastomer comprises at least one selected from the group consisting of styrene-based elastomers, olefin-based elastomers, polyester-based elastomers, urethane-based elastomers, polyamide-based elastomers, acrylic-based elastomers, and silicone-based elastomers. The photosensitive resin composition according to any one of claims 1 to 10, further comprising (F) an inorganic filler. A photosensitive resin composition for forming photovias, comprising the photosensitive resin composition according to any one of claims 1 to 11. A photosensitive resin composition for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of claims 1 to 11. A photosensitive resin film comprising the photosensitive resin composition according to any one of claims 1 to 11. A photosensitive resin film for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of claims 1 to 11. A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin composition according to any one of claims 1 to 11. A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin film according to claim 14. A semiconductor package comprising a semiconductor element mounted on the multilayer printed wiring board according to claim 16 or 17. A method for producing a multilayer printed wiring board, comprising the following steps (1) to (4):
Step (1): A step of laminating the photosensitive resin film according to claim 14 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.