JP7622353B2 - Photosensitive resin composition, photosensitive resin film, multilayer printed wiring board, semiconductor package, and method for manufacturing multilayer printed wiring board - Google Patents

Description

The present disclosure relates to a photosensitive resin composition, a photosensitive resin film, a multilayer printed wiring board 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 denser due to an increase in the number of circuit layers and finer wiring. In particular, signals used in mobile communication devices such as mobile phones, their base station equipment, servers, routers and other network infrastructure devices, and large computers are becoming faster and larger in capacity every year. Furthermore, with the spread of fifth-generation mobile communication system (5G) antennas that use radio waves in frequency bands above 6 GHz and the spread of autonomous driving of automobiles, etc., there is a growing demand for low transmission loss, and materials with low dielectric tangents are in high demand.

Examples of methods for manufacturing printed wiring boards include 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 hardened 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, as a method capable of forming a large number of vias at once, a method has been proposed 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 plurality of small diameter vias at once by a photolithography method (see, for example, Patent Document 2).
In addition, as a method for reducing the dielectric tangent of a photosensitive resin composition, a photosensitive resin composition containing (A) an active ester-based curing agent, (B) a carboxyl group-containing radical polymerizable compound, and (D) an epoxy resin has been proposed (see, for example, Patent Document 3).

Japanese Patent Application Publication No. 7-304931 JP 2017-116652 A JP 2013-214057 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 components are also problems, and it is said that these problems have been solved. In addition, Patent Document 3 states that by adding an active ester-based curing agent to a photosensitive resin composition used as a material for an interlayer insulating layer, it is possible to lower the dielectric tangent while improving heat resistance and water resistance.
However, in recent years, the trend toward lower transmission loss in semiconductor peripheral components has led to an even greater demand for improved dielectric properties of materials. Therefore, there is room for further improvement in the dielectric loss tangent of the photosensitive resin composition of Patent Document 2. In addition, the photosensitive resin composition of Patent Document 3 requires an active ester-based curing agent, but it would be of great technical significance to develop a method for reducing the dielectric loss tangent without relying on an active ester-based curing agent.

In addition, before wiring is formed, a desmear treatment (surface roughening treatment) is performed to improve adhesion with the copper foil. If the interlayer insulating layer made of a photosensitive resin composition has low desmear resistance, the unevenness increases and the outer wall of the via hole is also scraped off at the same time. This results in poor connection and the need for more metal plating, which increases manufacturing costs. Therefore, the photosensitive layer is required to have not only good via resolution but also excellent desmear resistance, but there is room for improvement in the desmear resistance of photosensitive layers made of conventional photosensitive resin compositions.

The object of the present invention is to provide a photosensitive resin composition having a low dielectric tangent and excellent desmear resistance, a photosensitive resin composition for forming photovias, and a photosensitive resin composition for an interlayer insulating layer. 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 producing the multilayer printed wiring board.

Means for Solving the Problems The present inventors have conducted intensive research and have found that the above-mentioned object can be achieved by a photosensitive resin composition containing the below-described components (A) and (B), in which the component (A) contains "(A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton", the epoxy resin (B) contains (B1) an epoxy resin having a condensed aromatic ring, and further contains (G) a curing accelerator.
That is, the present invention relates to the following [1] to [17].

[1] A photosensitive resin composition comprising (A) a photopolymerizable compound having an ethylenically unsaturated group, (B) an epoxy resin, and (C) a photopolymerization initiator, wherein the (A) photopolymerizable compound having an ethylenically unsaturated group comprises (A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton, the (B) epoxy resin comprises (B1) an epoxy resin having a condensed aromatic ring, and further comprises (G) a curing accelerator.
[2] The photosensitive resin composition according to the above [1], wherein the content of the epoxy resin containing a condensed aromatic ring (B1) is 0.5 to 10 mass% based on the total solid content of the photosensitive resin composition.
[3] The photosensitive resin composition according to the above [1] or [2], wherein the fused aromatic ring in the epoxy resin containing a fused aromatic ring (B1) is at least one selected from the group consisting of a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, and a chrysene ring.
[4] The photosensitive resin composition according to any one of the above [1] to [3], wherein the component (B) includes (B2) an epoxy resin other than the component (B1).
[5] The photosensitive resin composition according to any one of the above [1] to [4], wherein the component (B2) is at least one selected from the group consisting of biphenyl-type epoxy resins, biphenylaralkyl-type epoxy resins, bisphenol-based epoxy resins, and alicyclic skeleton-containing epoxy resins.
[6] The photosensitive resin composition according to the above [4] or [5], wherein the content of the component (B1) in the component (B) is 5 mass% or more.
[7] The photosensitive resin composition according to any one of the above [1] to [6], further comprising (D) an elastomer.
[8] The photosensitive resin composition according to any one of the above [1] to [7], further comprising (E) an inorganic filler.
[9] The photosensitive resin composition according to any one of the above [1] to [8], further comprising (F) a curing agent.
[10] A photosensitive resin composition for forming a photovia, comprising the photosensitive resin composition according to any one of [1] to [9] above.
[11] A photosensitive resin composition for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of [1] to [9] above.
[12] A photosensitive resin film comprising the photosensitive resin composition according to any one of [1] to [9] above.
[13] A photosensitive resin film for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of [1] to [9] above.
[14] A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin composition according to any one of [1] to [9] above.
[15] A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin film according to [12] above.
[16] A semiconductor package comprising the multilayer printed wiring board according to [14] or [15] above and a semiconductor element mounted thereon.
[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 the above item [12] onto one or both sides of a circuit board.
Step (2): A step of forming an interlayer insulating layer having vias by exposing and developing the photosensitive resin film laminated in the step (1).
Step (3): A step of roughening the via and the interlayer insulating layer.
Step (4): forming a circuit pattern on the interlayer insulating layer.

According to the present invention, it is possible to provide a photosensitive resin composition having a low dielectric tangent and excellent desmear resistance, a photosensitive resin composition for forming a photovia, and a photosensitive resin composition for an interlayer insulating layer. 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 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. It is also possible to provide a method for producing the multilayer printed wiring board.
Furthermore, by using the photosensitive resin composition of the present invention, the resolution of vias is also improved.

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 multiple substances corresponding to each component are present 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.
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) an epoxy resin, and (C) a photopolymerization initiator, in which the (A) photopolymerizable compound having an ethylenically unsaturated group contains (A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton, and further contains (G) a curing accelerator.
In this specification, the components may be referred to as component (A), component (B), component (C), component (A1), component (B1), component (G), etc., and other components may be abbreviated in the same manner. Furthermore, in this specification, the "resin component" refers to the components (A) and (B), etc., and also includes other components that may be contained as necessary (for example, components (C), (D), (F), (H), and (G), etc.), but does not include inorganic compounds such as inorganic fillers (E) and pigments (H) that may be contained as necessary, as described below. 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. In addition, the photosensitive resin composition of this embodiment has a low dielectric tangent, excellent desmear resistance, and good via resolution, so it is useful as an interlayer insulating layer of a multilayer printed wiring board, so the present invention also provides a photosensitive resin composition for an interlayer insulating layer. In this specification, the photosensitive resin composition includes a photosensitive resin composition for photovia formation and a photosensitive resin composition for an interlayer insulating 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>
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 nadiimide group, and a (meth)acryloyl group. As the ethylenically unsaturated group, a (meth)acryloyl group is preferable.
In this embodiment, the component (A) contains "(A1) a photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton" which will be described later. By containing the component (A1) in the component (A), the resolution of the via becomes good, and the dielectric tangent becomes sufficiently low even in a high frequency band of, for example, 10 GHz or more.
The component (A1) will be described in detail below.

((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 and low dielectric tangent, an alicyclic skeleton having 5 to 20 ring carbon atoms is preferable, an alicyclic skeleton having 5 to 18 ring carbon atoms is more preferable, an alicyclic skeleton having 6 to 18 ring carbon atoms is even more preferable, an alicyclic skeleton having 8 to 14 ring carbon atoms is particularly preferable, and an alicyclic skeleton having 8 to 12 ring carbon atoms is most preferable.
From the viewpoints of via resolution and low dielectric tangent, the alicyclic skeleton preferably consists of two or more rings, more preferably consists of 2 to 4 rings, and even more preferably consists of 3 rings. Examples of alicyclic skeletons having 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 and low dielectric tangent, a saturated dicyclopentadiene skeleton is preferred, and an alicyclic skeleton represented by the following general formula (a) (saturated dicyclopentadiene skeleton) is more preferred.

(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 the carbon atom represented by 1 or 2 and any of the carbon atoms represented by 3 or 4 in the following general formula (a').

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

From the viewpoints of enabling alkaline development and providing excellent via resolution, adhesive strength to plated copper, crack resistance, and electrical insulation reliability, the (A1) component is preferably an "(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 (A') component] with (a3) a saturated or unsaturated group-containing polybasic acid anhydride.

--(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 resins, bisphenol F type epoxy resins, and bisphenol S type epoxy resins; bisphenol-based novolac type epoxy resins such as bisphenol A novolac type epoxy resins and bisphenol F novolac type epoxy resins; novolac type epoxy resins other than the bisphenol-based novolac type epoxy resins, such as phenol novolac type epoxy resins, cresol novolac type epoxy resins, and biphenyl novolac type epoxy resins; phenol aralkyl type epoxy resins; biphenyl aralkyl type epoxy resins; stilbene type epoxy resins; naphthalene skeleton-containing epoxy resins such as naphthalene type epoxy resins, naphthol novolac type epoxy resins, naphthol type epoxy resins, naphthol aralkyl type epoxy resins, and naphthylene ether type epoxy resins; biphenyl type epoxy resins; xylylene type epoxy resins; dihydroanthracene type epoxy resins; aliphatic chain epoxy resins; and rubber-modified epoxy resins.

-(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 same applies as in the description of the ethylenically unsaturated group.
Examples of the ethylenically unsaturated group-containing monocarboxylic acid include acrylic acid, a dimer of acrylic acid, methacrylic acid, β-furfurylacrylic acid, β-styrylacrylic acid, cinnamic acid, crotonic acid, α-cyano Acrylic acid derivatives such as cinnamic acid; half-ester compounds which are the reaction products of hydroxyl group-containing acrylates and dibasic acid anhydrides; ethylenically unsaturated group-containing monoglycidyl ethers or ethylenically unsaturated group-containing monoglycidyl esters and dibasic acid anhydrides; and half-ester compounds which are reaction products with acid anhydrides. Among 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, pentaerythritol 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 in a ratio of 0.6 to 1.05 equivalents of the (a2) component per 1 equivalent of the epoxy group of the (a1) component, or it may be reacted in a ratio of 0.8 to 1.0 equivalents. By reacting in such a ratio, the photopolymerizability is improved, that is, the photosensitivity is increased, and the resolution of the vias tends to be improved.

The 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 preferable, and triphenylphosphine is more preferable.
The amount of the catalyst used is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and even more preferably 0.1 to 2 parts by mass, relative to 100 parts by mass of the total of the components (a1) and (a2). This amount tends to promote the reaction between the components (a1) and (a2).

In order to prevent polymerization during the reaction, it is preferable to use a polymerization inhibitor, such as hydroquinone, methylhydroquinone, hydroquinone monomethyl ether, catechol, pyrogallol, etc.
When a polymerization inhibitor is used, the amount of the polymerization inhibitor used is, from the viewpoint of improving the storage stability of the 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".

((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 of standard polystyrene ("PStQuick MP-H" and "PStQuick B", manufactured by Tosoh Corporation).
(GPC measuring device)
GPC device: High-speed GPC device "HCL-8320GPC", detector is differential refractometer or UV, manufactured by Tosoh Corporation Column: Column TSKgel SuperMultipore HZ-H (column length: 15 cm, column inner diameter: 4.6 mm), manufactured by Tosoh Corporation (measurement conditions)
Solvent: Tetrahydrofuran (THF)
Measurement temperature: 40°C
Flow rate: 0.35 mL/min Sample concentration: 10 mg/5 mL THF
Injection volume: 20 μL

((A2-1) Acid-modified ethylenically unsaturated group-containing epoxy derivative not containing an alicyclic skeleton)
The photopolymerizable compound (A) having an ethylenically unsaturated group may further include an "acid-modified ethylenically unsaturated group-containing epoxy derivative (A2-1) having no alicyclic skeleton" obtained by reacting a compound obtained by modifying (a21) an epoxy resin (not containing an alicyclic skeleton) with (a22) an ethylenically unsaturated group-containing organic acid with (a23) a saturated group- or unsaturated group-containing polybasic acid anhydride.

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, crack resistance, 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 photopolymerizable compound (A) having an ethylenically unsaturated group, a compound obtained by modifying the epoxy resin (a21) with an ethylenically unsaturated group-containing organic acid (a22), i.e., component (A'), with an isocyanate compound, "(A2-3) epoxy polyurethane resin" can also be used in combination. The component (A2-3) does not contain an alicyclic skeleton. The component (A2-3) may be used alone or in combination of two or more kinds.

(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 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 (A1).

((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 5 to 50 mass %, even more preferably 10 to 40 mass %, particularly preferably 10 to 30 mass %, and most preferably 15 to 25 mass %, based on the total solid content of the photosensitive resin composition.

Although the component (A) is not particularly limited, it is preferable to use the component (A1) and the component (Aiii) in combination from the viewpoint of photosensitive properties. In this case, the content ratio of the component (A1) to the component (Aiii) [(A1)/(Aiii)] (mass ratio) is preferably 1.5 to 20, more preferably 2 to 10, even more preferably 2.5 to 7, and particularly preferably 2.5 to 5.
From the viewpoint of via resolution, 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 65 to 85 mass%.
<(B) Epoxy Resin>

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 resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; bisphenol-based novolac type epoxy resins such as bisphenol A novolac type epoxy resin and bisphenol F novolac type epoxy resin; novolac type epoxy resins other than the above bisphenol-based novolac type epoxy resins such as phenol novolac type epoxy resin, cresol novolac type epoxy resin, and biphenyl novolac type epoxy resin; phenol aralkyl type epoxy resin; stilbene type epoxy resin; naphthalene type epoxy resin, naphthol novolac type epoxy resin; Epoxy resins that contain a naphthalene skeleton, such as rack-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 skeleton-containing 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 chain epoxy resins, such as branched alkyl chain epoxy resins; and rubber-modified epoxy resins.
The component (B) may be used alone or in combination of two or more types.

In this embodiment, the component (B) particularly contains an epoxy resin having a condensed aromatic ring (B1). Although the exact reason why the inclusion of the component (B1) allows the epoxy resin to achieve a low dielectric tangent is unclear, it is speculated that the condensed aromatic rings have an effect such as rigidity that makes it difficult for the epoxy resin to respond to changes in the electric field when an external electric field is applied, reducing molecular vibrations and thus reducing the amount of heat generated, thereby reducing transmission loss and lowering the dielectric tangent.
The number of rings condensed in the condensed aromatic ring in the epoxy resin containing a condensed aromatic ring (B1) is preferably 2 to 6 rings, more preferably 2 to 3 rings, and even more preferably 2 rings. The condensed aromatic ring is preferably at least one selected from the group consisting of a naphthalene ring, an anthracene ring, a phenanthrene ring, a pyrene ring, and a chrysene ring, and from the viewpoints of availability and low dielectric tangent, a naphthalene ring is more preferable.
Epoxy resins containing a naphthalene ring are usually referred to as naphthol-type epoxy resins, naphthalene-type epoxy resins, naphthalene skeleton-containing epoxy resins, etc. As the epoxy resin containing a naphthalene ring, commercially available products can also be used, and examples of commercially available products include naphthol-type epoxy resins ("Epotohto (registered trademark) ESN-475V" manufactured by Nippon Steel Chemical & Material Co., Ltd.), naphthalene-type epoxy resins ("HP4032D" and "HP4710" manufactured by DIC Corporation), and naphthalene skeleton-containing multifunctional epoxy resins ("NC-7000" manufactured by Nippon Kayaku Co., Ltd.).

Preferable examples of the epoxy resin containing a naphthalene ring include epoxy resins represented by any of the following general formulas (I) to (VIII).

(In general formula (I), R ¹ represents a hydrogen atom or a halogen-free organic group, and n ¹ represents an integer of 1 to 10.)

(In general formula (II), ⁿ² represents an integer of 1 to 10.)

(In general formula (III), ⁿ³ represents an integer of 1 to 10.)

(In formula (IV), ⁿ⁴ represents an integer of 1 to 10.)

(In formula (VI), ^Z1 represents a single bond or a halogen-free organic group.)

(In general formula (VII), ^Z2 represents a single bond or a halogen-free organic group. ^R2 represents a hydrogen atom or a halogen-free organic group.)

Examples of the halogen-free organic group represented by R ¹ in the general formula (I) and R ² in the general formula (VII) include alkyl groups having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 3), such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group; aryl groups having 6 to 18 (preferably 6 to 12) ring carbon atoms, such as a phenyl group and a naphthyl group; aralkyl groups having a total of 7 to 18 (preferably 7 to 13) carbon atoms, such as a benzyl group; and heteroaromatic groups having 5 to 18 (preferably 5 to 12) ring atoms, such as a pyridyl group.
Examples of the halogen-free organic group represented by ^Z1 in the general formula (VI) and ^Z2 in the general formula (VII) include alkylene groups having 1 to 10 carbon atoms (preferably 1 to 6, more preferably 1 to 3), such as a methylene group, a dimethylene group, a trimethylene group, a tetramethylene group, and a pentamethylene group; arylene groups having 6 to 18 (preferably 6 to 12) ring carbon atoms, such as a phenylene group, a naphthylene group, and an anthrylene group; and heteroaromatic groups having 5 to 18 (preferably 5 to 12) ring atoms, such as a pyridylene group.

Among the above-mentioned epoxy resins containing a naphthalene ring, from the viewpoint of low dielectric properties, the epoxy resin represented by the general formula (I) is preferred, and further, in the epoxy resin represented by the general formula (I), an epoxy resin in which R ¹ is a methyl group is more preferred.

In this embodiment, the (B) component may contain an epoxy resin (B2) other than the (B1) component, and it is preferable to contain the (B2) component that does not easily absorb ultraviolet light from the viewpoint of suppressing undercut of vias by increasing ultraviolet light absorption. Examples of epoxy resins other than the (B1) component include the same ones as the examples of the epoxy resins (excluding epoxy resins having condensed aromatic rings). Examples of the (B2) component that does not easily absorb ultraviolet light are not particularly limited, but are preferably biphenyl-type epoxy resins, biphenyl aralkyl-type epoxy resins, bisphenol-based epoxy resins, and aliphatic chain epoxy resins, and the like. From the viewpoint of the difficulty in absorbing ultraviolet light and low dielectric tangent, aliphatic chain epoxy resins are more preferable.
When the component (B) contains the component (B2) together with the component (B1), the component (B2) is preferably at least one selected from the group consisting of biphenyl-type epoxy resins, biphenylaralkyl-type epoxy resins, bisphenol-based epoxy resins, and aliphatic chain epoxy resins, and more preferably a biphenyl-type epoxy resin. The bisphenol-based epoxy resin may be, for example, a bisphenol F-type epoxy resin.
When the component (B) contains the component (B2) together with the component (B1), the content of the component (B1) in the component (B) is preferably 5 mass % or more from the viewpoint of a low dielectric tangent, and taking into consideration the resolution of vias, adhesive strength to plated copper, crack resistance, electrical insulation reliability, and the like, the content is more preferably 5 to 95 mass %, even more preferably 25 to 90 mass %, particularly preferably 50 to 85 mass %, and most preferably 60 to 85 mass %.

As the component (B2), commercially available products can be used, for example, 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, "YSLV-80XY" manufactured by Nippon Steel Chemical & Material Co., Ltd.), and epoxy resins having a biphenyl structure ("NC-3000-H" and "NC-300" manufactured by Nippon Kayaku Co., Ltd.). 0-L, "NC-3500"), Mitsubishi Chemical Corporation ("YX4000HK", "YL6121"), anthracene type epoxy resin (Mitsubishi Chemical Corporation "YX8800"), glycerol type epoxy resin (Nippon Steel Chemical & Material Co., Ltd. "ZX1542"), naphthylene ether type epoxy resin (DIC Corporation "EXA7311-G4"), cresol novolac type epoxy resin (DIC Corporation "EPICLON N-680"), branched alkyl chain epoxy resin (Nissan Chemical Co., Ltd. "FOLDI-E201"), as well as Mitsubishi Chemical Corporation's "YL9057" (multifunctional novolac type epoxy resin) and "YL9058".

(Content of component (B1))
The content of the epoxy resin containing a condensed aromatic ring (B1) is preferably 0.5 to 40 mass%, more preferably 1 to 30 mass%, even more preferably 2 to 25 mass%, particularly preferably 5 to 25 mass%, and most preferably 8 to 20 mass%, based on the total solid content of the photosensitive resin composition. When the content of the component (B1) is 0.5 mass% or more based on the total solid content of the photosensitive resin composition, the dielectric loss tangent tends to be sufficiently low, and when it is 40 mass% or less, the resolution of the vias tends to be good.

(Content of component (B))
In addition, in the photosensitive resin composition of the present embodiment, the content of the component (B) is, from the viewpoints of adhesive strength with plated copper, insulation reliability, and heat resistance, preferably 1 to 30 mass %, more preferably 3 to 25 mass %, even more preferably 5 to 25 mass %, and particularly preferably 10 to 25 mass %, based on the total solid content of the photosensitive resin composition.

<(C) Photopolymerization initiator>
The component (C) 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 (C) 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 suitable 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, thioxanthones, and benzophenones are preferred, with 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2,4-diethylthioxanthone, and 4,4'-bis(diethylamino)benzophenone being more preferred. Acetophenones and benzophenones have the advantage that they are less volatile and less likely to generate outgassing, and thioxanthones have the advantage that they can be photocured even in the visible light range.
The component (C) may be used alone or in combination of two or more. When using two or more in combination, it is preferable to use acetophenones, thioxanthones, and benzophenones in combination, and it is more preferable to use 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, 2,4-diethylthioxanthone, and 4,4'-bis(diethylamino)benzophenone in combination.

(Content of component (C))
The content of the (C) component is not particularly limited, but is preferably 0.1 to 15 mass%, more preferably 0.15 to 5 mass%, even more preferably 0.2 to 1.5 mass%, particularly preferably 0.2 to 1.0 mass%, and most preferably 0.25 to 0.80 mass%, based on the total solid content of the photosensitive resin composition. If the (C) component content 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.

<(C') Photopolymerization Initiator Auxiliary Agent>
The photosensitive resin composition of the present embodiment may contain a photopolymerization initiation aid (C') together with the component (C). Examples of the photopolymerization initiation aid (C') include tertiary amines such as N,N-dimethylaminobenzoic acid ethyl ester, N,N-dimethylaminobenzoic acid isoamyl ester, pentyl-4-dimethylaminobenzoate, triethylamine, and triethanolamine. The component (C') may be used alone or in combination of two or more.
When the photosensitive resin composition of the present embodiment contains the component (C'), 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 (C').

<(D) Elastomer>
The photosensitive resin composition of the present embodiment may contain an elastomer as component (D), and preferably does. By containing component (D), the photosensitive resin composition tends to have excellent via resolution, adhesive strength with plated copper, and electrical insulation reliability. In addition, component (D) 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 (D), an elastomer that is liquid at 25°C is preferred.
The component (D) 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 (D) 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 is particularly preferably an olefin-based elastomer, from the viewpoints of compatibility, solubility, and adhesive strength with plated copper.

(styrene elastomer)
Examples of the styrene-based elastomer include styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer, styrene-ethylene-propylene-styrene block copolymer, etc. One type of styrene-based elastomer may be used alone, or two or more types may be used in combination.
Examples of components constituting the styrene-based elastomer include styrene; and styrene derivatives such as α-methylstyrene, 3-methylstyrene, 4-propylstyrene, and 4-cyclohexylstyrene.
The styrene-based elastomer preferably has a number average molecular weight of 1,000 to 50,000, and more preferably has a number average molecular weight of 3,000 to 20,000.
In this specification, the number average molecular weight is a value determined in terms of standard polystyrene by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent.

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

(Olefin elastomer)
The olefin elastomer is, for example, a polymer or copolymer of an α-olefin having 2 to 20 carbon atoms, such as ethylene, propylene, 1-butene, 1-hexene, or 4-methyl-pentene. The olefin elastomer may have a hydroxyl group at the molecular end, and preferably has a hydroxyl group at the molecular end. One type of olefin elastomer may be used alone, or two or more types may be used in combination.
Suitable examples of olefin elastomers include polyethylene, polybutadiene, hydroxyl group-containing polybutadiene, hydroxyl group-containing polyisopropylene, ethylene-propylene copolymer (EPR), ethylene-propylene-diene copolymer (EPDM), etc. Also included are copolymers of the above-mentioned α-olefins having 2 to 20 carbon atoms with non-conjugated dienes having 2 to 20 carbon atoms, such as dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylenenorbornene, ethylidenenorbornene, butadiene, isoprene, etc. Still further examples include carboxy-modified NBR obtained by copolymerizing butadiene-acrylonitrile copolymer with methacrylic acid.
The olefin elastomer preferably has a number average molecular weight of 1,000 to 8,000, more preferably 1,500 to 6,500.

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

(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 (D-1). The diol compounds may be used alone or in combination of two or more.

(In general formula (D-1), X ^D1 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 D1} and R ^D2 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 (D-1), examples of the alkylene group having 1 to 10 carbon atoms represented by X ^D1 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, from the viewpoints of via resolution, adhesive strength with plated copper, and electrical insulation reliability, an alkylene group having 1 to 3 carbon atoms is preferable, and a methylene group is more preferable.
Examples of the alkylidene group having 2 to 10 carbon atoms represented by ^XD1 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 ^XD1 include a cyclopentylene group, a cyclohexylene group, and a cyclooctylene group.
Among the above, ^XD1 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 (D-1), examples of the halogen atom represented by R ^{1 D1} and R ^{1 D2} 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 ^D1 and R ^D2 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 (D-1'), X ^D1 , R ^D1 and p are all the same as those in formula (D-1), and the preferred embodiments are also the same.)

Examples of aromatic diols represented by the general formula (D-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.), and "Espel (registered trademark)" (manufactured by Hitachi Chemical Co., Ltd.).

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.

Commercially available polyester elastomers may be used, and examples of commercially available products other than those mentioned above include Teslac 2505-63 (manufactured by Hitachi Chemical Co., Ltd., "Teslac" is a registered trademark).

(Urethane elastomer)
The urethane-based elastomer preferably includes, for example, one containing a hard segment consisting of a short-chain diol and a diisocyanate, and a soft segment consisting of a polymer (long-chain) diol and a diisocyanate. The urethane-based elastomer may be used alone or in combination of two or more kinds.
Examples of the polymeric (long-chain) diol include polypropylene glycol, polytetramethylene oxide, poly(1,4-butylene adipate), poly(ethylene-1,4-butylene adipate), polycaprolactone, poly(1,6-hexylene carbonate), poly(1,6-hexylene-neopentylene adipate), etc. The number average molecular weight of the polymeric (long-chain) diol is preferably 500 to 10,000.
Examples of the short-chain diol include ethylene glycol, propylene glycol, 1,4-butanediol, and bisphenol A. The number average molecular weight of the short-chain diol is preferably 48 to 500.
The urethane elastomer preferably has a number average molecular weight of 1,000 to 25,000, more preferably 1,500 to 20,000, and even more preferably 2,000 to 15,000.

The urethane-based elastomer may be a commercially available product, such as Nipporan 3116 (manufactured by Tosoh Corporation, "Nipporan" is a registered trademark), PANDEX T-2185, T-2983N (both manufactured by DIC Corporation), the Miractoran series (manufactured by Nippon Miractoran Co., Ltd., "Miractran" is a registered trademark), and the Hitaloid series (manufactured by Hitachi Chemical Co., Ltd., "Hitaroid" is a registered trademark).

(Polyamide elastomer)
Polyamide elastomers are roughly classified into two types: polyether block amide type, which uses polyamide for the hard segment and polyether for the soft segment; and polyether ester block amide type, which uses polyamide for the hard segment and polyester for the soft segment.
Specific examples of the polyamide-based elastomer include block copolymers having polyamide as a hard segment component and polybutadiene, butadiene-acrylonitrile copolymer, styrene-butadiene copolymer, polyisoprene, ethylene propylene copolymer, polyether, polyester, polybutadiene, polycarbonate, polyacrylate, polymethacrylate, polyurethane, silicone rubber, etc. One type of polyamide-based elastomer may be used alone, or two or more types may be used in combination.
The polyamide elastomer preferably has a number average molecular weight of 1,000 to 50,000, and more preferably 2,000 to 30,000.

Commercially available polyamide elastomers may be used, and examples of commercially available products include UBE polyamide elastomers (manufactured by Ube Industries, Ltd.), DAIAMID (manufactured by Daicel-Evonik Ltd., "DAIAMID" is a registered trademark), PEBAX (manufactured by Toray Industries, Inc.), GRILLON ELY (manufactured by M-Chemie Japan, Inc., "GRILLON" is a registered trademark), NOVAMID (manufactured by Mitsubishi Chemical Corporation), and GLYX (manufactured by Toyobo Co., Ltd., "GLYX" is a registered trademark).

(Acrylic elastomer)
The acrylic elastomer may be, for example, a polymer of a raw material monomer mainly composed of an acrylic acid ester. Suitable examples of the acrylic acid ester include ethyl acrylate, butyl acrylate, methoxyethyl acrylate, and ethoxyethyl acrylate. The crosslinking point monomer may be a copolymer of glycidyl methacrylate, allyl glycidyl ether, or acrylonitrile, ethylene, or the like. Specific examples include acrylonitrile-butyl acrylate copolymer, acrylonitrile-butyl acrylate-ethyl acrylate copolymer, and acrylonitrile-butyl acrylate-glycidyl methacrylate copolymer. The acrylic elastomer may be used alone or in combination of two or more kinds.
The acrylic elastomer preferably has a number average molecular weight of 1,000 to 50,000, and more preferably 2,000 to 30,000.

(Silicone elastomer)
The silicone elastomer is an elastomer mainly composed of organopolysiloxane, and is classified into, for example, polydimethylsiloxane elastomers, polymethylphenylsiloxane elastomers, polydiphenylsiloxane elastomers, etc. The silicone elastomers may be used alone or in combination of two or more kinds.
The silicone elastomer preferably has a number average molecular weight of 1,000 to 50,000, and more preferably 2,000 to 30,000.

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

(Other elastomers)
In addition, the component (D) 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 (D))
When the photosensitive resin composition of the present embodiment contains the (D) component, the content thereof is preferably 0.5 to 20 mass%, more preferably 1.0 to 20 mass%, further preferably 1.0 to 15 mass%, particularly preferably 1.0 to 10 mass%, and most preferably 1.0 to 4 mass%, based on the total solid content of the photosensitive resin composition. If the content of the (D) component 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 (D) component 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.

<(E) Inorganic filler>
The photosensitive resin composition of the present embodiment may contain an inorganic filler as the component (E), and preferably contains an inorganic filler. By containing an inorganic filler, low thermal expansion In the thermosetting resin composition that has been conventionally used as an interlayer insulating layer of a multilayer printed wiring board, the thermal expansion is reduced by including an inorganic filler. However, when an inorganic filler is added to a photosensitive resin composition, the inorganic filler causes light scattering and impedes development, making it difficult to achieve low thermal expansion by adding a large amount of the inorganic filler. As described above, the inclusion of an inorganic filler poses new problems unique to photosensitive resin compositions. However, the photosensitive resin composition of the present embodiment does not require a large amount of inorganic filler. Even if the photosensitive resin composition contains the fluorine-containing compound, the resolution of the vias tends to be high. Therefore, the photosensitive resin composition of the present embodiment can achieve both low thermal expansion and high resolution of the vias. It is.

Examples of the component (E) 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 component ( _E ), one type may be used alone, or two or more types may be used in combination.

From the viewpoint of via resolution, the average particle size of component (E) 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. Furthermore, a component (E) having a smaller particle size may be used in combination, and the average particle size of such a component (E) is preferably 20 to 500 nm, more preferably 30 to 350 nm, even more preferably 50 to 300 nm, particularly preferably 80 to 300 nm, and most preferably 140 to 300 nm. Here, the average particle size of component (E) is the volume average particle size of the inorganic filler in a dispersed state 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 with a submicron particle analyzer (manufactured by Beckman Coulter, Inc., product name: N5) in accordance with the international standard ISO 13321 at a refractive index of 1.38, and the particle diameter at an integrated value of 50% (volume basis) in the particle size distribution is taken as the average particle diameter (volume average particle diameter). In addition, the (E) component contained in the photosensitive resin film and interlayer insulating layer provided on the carrier film can also be measured by diluting (or dissolving) the composition 1,000 times (volume ratio) with a solvent as described above, and then using the above-mentioned submicron particle analyzer.

From the viewpoints of heat resistance and low thermal expansion, it is preferable that component (E) contains silica, and it is more preferable that it is silica. In addition, component (E) 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.

(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 5 to 75 mass%, more preferably 10 to 65 mass%, further preferably 20 to 60 mass%, particularly preferably 30 to 55 mass%, and most preferably 40 to 50 mass%, based on the total solid content of the photosensitive resin composition. If the content of the component (E) is within the above range, the mechanical strength, heat resistance, via resolution, and the like can be improved.

<(F) Curing Agent>
The photosensitive resin composition of the present embodiment preferably contains a curing agent from the viewpoint of further improving various properties such as heat resistance and low dielectric tangent.
Examples of the (F) component include phenolic resin-based curing agents, acid anhydride-based curing agents, amine-based curing agents, hydrazide-based curing agents, and active ester-based curing agents. Among these, phenolic resin-based curing agents are preferred. The (F) component may be used alone or in combination of two or more.
Examples of the phenolic resin-based curing agent include novolac-type phenolic resins such as phenol novolac resins and cresol novolac resins; resol-type phenolic resins, and among these, novolac-type phenolic resins are preferred from the viewpoint of improving reliability. As the novolac-type phenolic resin, a commercially available product may be used, and examples of the commercially available product include phenol novolac resin "Phenolite (registered trademark) TD-2090", triazine-containing phenol novolac resin "Phenolite (registered trademark) LA-1356" and "Phenolite (registered trademark) LA7050 series", triazine-containing cresol novolac resin "Phenolite (registered trademark) LA-3018" and "Phenolite (registered trademark) LA-3018-50P" (all manufactured by DIC Corporation).
Examples of the acid anhydride curing agent include phthalic anhydride, benzophenonetetracarboxylic dianhydride, and methyl hymic acid anhydride.
Examples of the amine-based curing agent include dicyandiamide, diaminodiphenylmethane, and guanylurea.
When the photosensitive resin composition of the present embodiment contains the component (F), the content thereof is preferably 0.01 to 20 mass %, more preferably 0.05 to 15 mass %, still more preferably 0.05 to 5 mass %, and particularly preferably 0.05 to 1 mass %, based on the total amount of the resin components in the photosensitive resin composition.

<(G) Curing Accelerator>
The photosensitive resin composition of the present embodiment contains a curing accelerator as the (G) component, and thus has a lower dielectric tangent in a high frequency band, for example, 10 GHz or higher. The exact mechanism by which such a result is obtained is unclear, but it is considered as follows. In a photosensitive resin film formed from a photosensitive resin composition, it is considered that the reaction rate between the acidic substituent of the (A1) component and the (B) epoxy resin is not very high, but by containing a curing accelerator, they react efficiently to improve the crosslink density, and as a result, the rigidity is increased, and the molecular motion following the change in the electric field is suppressed, the heat generation is reduced, and the transmission loss is suppressed, resulting in a lower dielectric tangent.
The (G) curing accelerator may be any that can accelerate the crosslinking and curing of the (A1) component and the (B) component, and examples thereof include imidazole curing accelerators, amine curing accelerators, guanidine curing accelerators, phosphonium curing accelerators, and metal curing accelerators. Among these, imidazole curing accelerators are preferred from the viewpoint of the effect of improving the low dielectric tangent. The (G) component may be used alone or in combination of two or more.

Examples of the imidazole-based curing accelerator include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 2-phenylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole.
Examples of the amine-based curing accelerator include tertiary amines such as trimethylamine, N,N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmorpholine, hexa(N-methyl)melamine, 2,4,6-tris(dimethylaminophenol), and m-aminophenol.
Examples of the guanidine curing accelerator include 1,1,3,3-tetramethylguanidine, 1-(1,1,3,3-tetramethylbutyl)guanidine, and the like.
Examples of the phosphonium curing accelerator include phosphonium salts such as tri-n-butyl(2,5-dihydroxyphenyl)phosphonium bromide and hexadecyltributylphosphonium chloride.

Examples of the metal-based curing accelerator include organometallic curing accelerators such as organometallic salts and organometallic complexes of transition metals and Group 12 metals. Examples of metals include copper, cobalt, manganese, iron, nickel, zinc, tin, etc. Examples of the organometallic salt include carboxylates, such as naphthenates such as cobalt naphthenate and zinc naphthenate; 2-ethylhexanoates such as cobalt 2-ethylhexanoate and zinc 2-ethylhexanoate; zinc octoate, tin octoate, tin stearate, zinc stearate, etc.
Examples of the organometallic complex include chelate complexes such as acetylacetone complexes. Specific examples thereof include organocobalt complexes such as cobalt(II) acetylacetonate and cobalt(III) acetylacetonate; organocopper complexes such as copper(II) acetylacetonate; organozinc complexes such as zinc(II) acetylacetonate; organoiron complexes such as iron(III) acetylacetonate; organonickel complexes such as nickel(II) acetylacetonate; and organomanganese complexes such as manganese(II) acetylacetonate.

In the photosensitive resin composition of the present embodiment, the content of the component (G) is preferably 0.01 to 20 mass %, more preferably 0.05 to 15 mass %, even more preferably 0.05 to 5 mass %, particularly preferably 0.1 to 2.5 mass %, and most preferably 0.2 to 1.5 mass %, based on the total amount of resin components in the photosensitive resin composition.
When the content of the component (G) is 0.01% by mass or more based on the total amount of the resin components of the photosensitive resin composition, the effect of improving the low dielectric tangent tends to be obtained, and when it is 20% by mass or less, the storage stability of the photosensitive resin composition tends to be good.

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

(Content of component (H))
When the photosensitive resin composition of the present embodiment contains the component (H), the content thereof is preferably 0.01 to 5 mass %, more preferably 0.03 to 3 mass %, and even more preferably 0.05 to 2 mass %, based on the total solid content of the photosensitive resin composition, from the viewpoint of adjusting photosensitivity, etc.

<(I) Thermosetting resin (excluding the epoxy resin (B) and the component (F))>
The photosensitive resin composition of the present embodiment may further contain a thermosetting resin (excluding the epoxy resin (B) and the component (F)) from the viewpoints of adhesive strength with plated copper, insulation reliability, and heat resistance.
Examples of the thermosetting resin include 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. Furthermore, the thermosetting resin is not particularly limited to these, and any known thermosetting resin can be used.
The component (I) may use one type alone, or two or more types in combination.

(Content of component (I))
When the photosensitive resin composition of the present embodiment contains component (I), the content thereof is preferably 1 to 30 mass %, more preferably 1 to 15 mass %, and even more preferably 1 to 10 mass %, based on the total solid content of the photosensitive resin composition, from the viewpoints of adhesive strength with plated copper, insulation reliability, and heat resistance.

<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 can be used. The diluent may be used alone or in combination of two or more.

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

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

[Photosensitive resin film, 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 avoiding diffusion of the diluent during the manufacturing process of the multilayer printed wiring board.

The photosensitive resin film of this embodiment has good via resolution and a low dielectric tangent, 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 this embodiment as well.
In the case of wet development, a developer corresponding to the photosensitive resin composition is used to develop the photosensitive resin composition by a known development method. Examples of the development method include a dip method, a battle method, a spray method, a brushing method, a slapping method, a scraping method, a swing immersion method, and the like. 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, and tends to be smaller than the size of the via produced 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 formation process (4))
The circuit pattern forming step (4) is a step of forming a circuit pattern on the interlayer insulating layer after the roughening treatment step (3).
From the viewpoint of forming fine wiring, 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 K.K., and "Surucup (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 the photosensitive resin composition of this embodiment also has good pattern resolution, so 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 the respective examples were evaluated by the methods described below.

[1. Evaluation of dielectric tangent]
The protective film was peeled off and removed from the photosensitive resin film with the carrier film and protective film produced in each example. Next, another sheet of the same photosensitive resin film was prepared, and the exposed photosensitive resin films were placed so as to be in contact with each other, and then a lamination process was performed using a press-type vacuum laminator (manufactured by Meiki Seisakusho Co., Ltd., product name "MVLP-500"). The lamination conditions were a press hot plate temperature of 75°C, a vacuum drawing time of 20 seconds, a lamination press time of 20 seconds, an atmospheric pressure of 4 kPa or less, and a pressure of 0.4 MPa. After the lamination process, the laminate was left at room temperature for 1 hour or more to obtain an evaluation laminate in which the photosensitive resin film was sandwiched between the carrier films.

Next, the obtained evaluation laminate was exposed to light at 400 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 170°C for 1 hour to obtain a cured film.
The dielectric loss tangent of the cured film at 10 GHz was measured by a cavity resonator method using a vector network analyzer E8364B manufactured by Agilent Technologies, Inc., and a CP531 (10 GHz resonator) and CPMA-V2 (program) manufactured by Kanto Electronics Application Development Co., Ltd., at an atmospheric temperature of 25° C.
The dielectric loss tangent is preferably 0.0097 or less.

[2. Evaluation of desmear resistance]
A laminate for evaluation was obtained in the same manner as in [1. Evaluation of dielectric tangent] above.
Next, the obtained laminate for evaluation was immersed in a swelling liquid "Swelling Dip Securigant P" (aqueous solution of glycol ethers and sodium hydroxide, manufactured by Atotech Japan Co., Ltd.) at 70°C for 10 minutes, and then washed with water at 25°C for 3 minutes. Next, the laminate for evaluation was immersed in a roughening liquid "Concentrate Compact P" (aqueous solution of _KMnO4 : 60 g/L, NaOH: 40 g/L, manufactured by Atotech Japan Co., Ltd.) at 80°C for 30 minutes, and then washed with water at 50°C for 1 minute. Finally, the laminate for evaluation was immersed in a neutralizing liquid "Reduction Shoreusin Securigant P" (aqueous solution of sulfuric acid, manufactured by Atotech Japan Co., Ltd.) at 40°C for 5 minutes, and then washed with water at 25°C for 3 minutes. Then, it was dried at 105°C for 10 minutes. In this manner, the desmear treatment was performed.
The weight loss (g/m ² ) after the desmear treatment relative to the dry weight before the desmear treatment was calculated and used as an index of desmear resistance. The smaller the weight loss after the desmear treatment, the better the desmear resistance.

<Comparative Example 1, Examples 1 to 5>
(Preparation of Photosensitive Resin Composition)
Compositions were formulated according to the formulations and amounts shown in Table 1, and methyl ethyl ketone was used as a diluent to prepare photosensitive resin compositions having a solids concentration of 65% by mass.
(Preparation of Photosensitive Resin Film)
A polyethylene terephthalate film (HPE, product name, manufactured by Teijin DuPont) having a thickness of 25 μm 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 would be 25 μm, and the composition was dried at 100° C. for 10 minutes using a hot air convection dryer to form a photosensitive resin film (photosensitive layer).
Next, a biaxially oriented polypropylene film (MA-411, product name, manufactured by Oji F-Tex Co., Ltd.) was laminated as a protective film on the surface of the photosensitive resin film (photosensitive layer) opposite the surface in contact with the carrier film, to produce a photosensitive resin film in which the carrier film and the protective film were laminated together.
The prepared photosensitive resin film was exposed to light using a stepper exposure device "UX-2240" (manufactured by Ushio Inc.). After exposure, the film was left at room temperature for 30 minutes, and then the photosensitive resin composition in the unexposed area was spray-developed for 60 seconds using a 1% by mass aqueous solution of sodium carbonate at 30°C, whereby the opening of a via was confirmed.
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):
Photopolymerizable compound having an ethylenically unsaturated group as well as an acidic substituent and an alicyclic skeleton: "ZXR-1807H" (product name, manufactured by Nippon Kayaku Co., Ltd.) [Component (A1)]
Dipentaerythritol pentaacrylate [Component (Aiii)]
(B) component;
Epoxy resin having a condensed aromatic ring: naphthol-type epoxy resin "Epotohto (registered trademark) ESN-475V" (product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.), which corresponds to the epoxy resin represented by the general formula (II) above. [Component (B1)]
Biphenyl-type epoxy resin: "NC-3000-L" (product name, manufactured by Nippon Kayaku Co., Ltd.) [Component (B2)]
Component (C);
Photopolymerization initiator 1: 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-1-propanone, acetophenones Photopolymerization initiator 2: 2,4-diethylthioxanthone, thioxanthones Photopolymerization initiator 3: 4,4'-bis(diethylamino)benzophenone, benzophenones (D) component;
Elastomer: "Epolead (registered trademark) PB3600" (trade name, manufactured by Daicel Corporation), epoxidized polybutadiene (E) component;
Silica 1: "SC-2050-LNF" (manufactured by Admatechs Co., Ltd., average particle size 0.5 μm, product name)
Silica 2: "KC180G-LJA" (manufactured by Admatechs Co., Ltd., average particle size 180 nm, product name)
Component (F);
Hardener 1: "Phenolite (registered trademark) LA-7052" (manufactured by DIC Corporation, product name)
Component (G);
Curing accelerator 1: 2-ethyl-4-methylimidazole (manufactured by Shikoku Chemicals Corporation)
Curing accelerator 2: 1-benzyl-2-phenylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.)
Curing accelerator 3: Epoxy adduct imidazole having the following structure (manufactured by Mitsubishi Chemical Corporation)

Curing accelerator 4: 2-undecylimidazole (manufactured by Shikoku Chemical Industry Co., Ltd.)
Curing accelerator 5: Isocyanate masked imidazole "G8009L" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name)

From Table 1, it is seen that in Examples 1 to 5, a lower dielectric tangent was obtained than in Comparative Example 1, and the desmear resistance was excellent.
Furthermore, as shown below, a comparison was made between the case where the component (B1) was blended and the case where the component (B1) was not blended.

<Comparative Examples 2 to 6, Example 6>
(Preparation of Photosensitive Resin Composition)
Compositions were formulated according to the formulations and amounts shown in Table 2, and methyl ethyl ketone was used as a diluent to prepare photosensitive resin compositions with a solids concentration of 65 mass %.
(Preparation of Photosensitive Resin Film)
A polyethylene terephthalate film (HPE, product name, manufactured by Teijin DuPont) having a thickness of 25 μm 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 would be 25 μm, and the composition was dried at 100° C. for 10 minutes using a hot air convection dryer to form a photosensitive resin film (photosensitive layer).
Next, a biaxially oriented polypropylene film (MA-411, product name, manufactured by Oji F-Tex Co., Ltd.) was laminated as a protective film on the surface of the photosensitive resin film (photosensitive layer) opposite the surface in contact with the carrier film, to produce a photosensitive resin film in which the carrier film and the protective film were laminated together.
The photosensitive resin film thus produced was also evaluated according to the above-mentioned methods. The results are shown in Table 2.

The components in Table 2 are the same as those in Table 1. Components not listed in Table 1 are shown below.
(B) component;
Bisphenol-based epoxy resin: "YSLV-80XY", bisphenol F type epoxy resin (product name, manufactured by Nippon Steel Chemical & Material Co., Ltd.) [Component (B2)]
Epoxy resin "YL9057": multifunctional novolac type epoxy resin, product name, manufactured by Mitsubishi Chemical Corporation, [component (B2)]
Epoxy resin "YL9058"; trade name, manufactured by Mitsubishi Chemical Corporation, [component (B2)]
Aliphatic chain epoxy resin: "FOLDI-E201" (product name, manufactured by Nissan Chemical Industries, Ltd.), branched alkyl chain epoxy resin, [component (B2)]
Component (F);
Hardener 2: "EXB-8" (product name, manufactured by DIC Corporation), active ester hardener

From Table 2, it can be seen that in a photosensitive resin composition containing component (A1), in order to significantly improve the low dielectric tangent while improving the desmear resistance, both (B1) an epoxy resin having a condensed aromatic ring and (G) a curing accelerator are essential.

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 (17)

A photosensitive resin composition comprising (A) a photopolymerizable compound having an ethylenically unsaturated group, (B) an epoxy resin, and (C) a photopolymerization initiator, wherein the (A) photopolymerizable compound having an ethylenically unsaturated group comprises (A1) a photopolymerizable compound having an acidic substituent and an alicyclic skeleton in addition to an ethylenically unsaturated group, and the (A1) component is an acid-modified ethylenically unsaturated group- and alicyclic skeleton-containing epoxy derivative (A1-1) obtained by reacting a compound obtained by modifying (a1) an alicyclic skeleton-containing epoxy resin with (a2) an ethylenically unsaturated group-containing organic acid, with (a3) a saturated group- or unsaturated group-containing polybasic acid anhydride, and the (a1) component is an epoxy resin represented by the following general formula (a1-1) or an epoxy resin having a structural unit represented by the following general formula (a1-2):
The photosensitive resin composition according to claim 1, wherein the epoxy resin (B) contains an epoxy resin (B1) having a condensed aromatic ring, the component (B1) being an epoxy resin represented by the following general formula (II) , and further containing a curing accelerator (G):

(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. m1 is an integer of 0 to 6, m2 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. m1 is an integer of 0 to 6.)

(In the general formula (II), ⁿ² represents an integer of 1 to 10.) 2. The photosensitive resin composition according to claim 1, wherein the content of the epoxy resin having a condensed aromatic ring (B1) is 0.5 to 40 mass % based on the total solid content of the photosensitive resin composition. 3. The photosensitive resin composition according to claim 1, further comprising, as the component (B), (B2) an epoxy resin other than the component (B1). 4. The photosensitive resin composition according to claim 3 , wherein the component (B2) is at least one selected from the group consisting of biphenyl-type epoxy resins, biphenyl aralkyl-type epoxy resins, bisphenol-based epoxy resins, and alicyclic skeleton-containing epoxy resins. 5. The photosensitive resin composition according to claim 3 , wherein the content of the component (B1) in the component (B) is 5 mass% or more. The photosensitive resin composition according to any one of claims 1 to 5 , further comprising (D) an elastomer. The photosensitive resin composition according to any one of claims 1 to 6 , further comprising (E) an inorganic filler. The photosensitive resin composition according to any one of claims 1 to 7 , further comprising (F) a curing agent. The photosensitive resin composition according to any one of claims 1 to 8, wherein the (G) curing accelerator is at least one selected from the group consisting of imidazole-based curing accelerators, amine-based curing accelerators, guanidine-based curing accelerators, phosphonium-based curing accelerators, and metal-based curing accelerators. A photosensitive resin composition for forming a photovia, comprising the photosensitive resin composition according to any one of claims 1 to 9 . A photosensitive resin composition for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of claims 1 to 9 . A photosensitive resin film comprising the photosensitive resin composition according to any one of claims 1 to 9 . A photosensitive resin film for an interlayer insulating layer, comprising the photosensitive resin composition according to any one of claims 1 to 9 . A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin composition according to any one of claims 1 to 9 . A multilayer printed wiring board comprising an interlayer insulating layer formed using the photosensitive resin film according to claim 12 . A semiconductor package comprising the multilayer printed wiring board according to claim 14 or 15 mounted with a semiconductor element. 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 12 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.