TWI807464B - Printed wiring board and manufacturing method of printed wiring board - Google Patents

Abstract

This application provides a printed circuit board, which has through holes with high conduction reliability. The printed circuit board (11) of this case has: a first conductor layer (8); a second conductor layer (3); an interlayer insulating layer (7); a through hole (6), which penetrates the interlayer insulating layer (7); and a through hole conductor (9), which is arranged in the through hole (6). The interlayer insulating layer (7) is a cured product of a negative-type photosensitive resin composition containing: a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C). The through hole (6) has: a first end (61) on the first conductor layer (8) side; a second end (62) on the second conductor layer (3) side; and a small diameter portion (63) located between the first end (61) and the second end (62) and having a diameter smaller than that of the second end (62).

Description

Printed wiring board and method for manufacturing printed wiring board

This case generally relates to a printed circuit board and a method for manufacturing a printed circuit board, and specifically relates to a printed circuit board and a method for manufacturing the aforementioned printed circuit board. The printed circuit board is provided with an interlayer insulating layer, and the interlayer insulating layer has through holes and through hole conductors.

In printed wiring boards, via holes are sometimes formed in interlayer insulating layers.

For example, Patent Document 1 discloses a method for manufacturing a multilayer printed circuit board, which includes: irradiating a carbon dioxide laser on a plastic film that has been made to adhere to the surface of an insulating layer containing more than 35% by mass of inorganic filler material, and forming a step of blind via holes with a top diameter of 100 μm or less. [Prior Art Literature] (patent documents)

Patent Document 1: Japanese Patent Laid-Open No. 2016-181731

The problem to be solved in this case is to provide a printed circuit board and a method for manufacturing the aforementioned printed circuit board. The printed circuit board has through holes with high conduction reliability. [Technical means to solve the problem]

A printed circuit board according to one aspect of the present case includes: a first conductor layer; a second conductor layer; an interlayer insulating layer interposed between the first conductor layer and the second conductor layer; a through hole penetrating the interlayer insulating layer; and a via conductor disposed in the through hole and conducting the first conductor layer and the second conductor layer. The aforementioned interlayer insulating layer is a cured product of a negative-type photosensitive resin composition containing a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C). The through hole has: a first end which is an end on the side of the first conductor layer; a second end which is an end on the side of the second conductor layer; and a small diameter portion which is located between the first end and the second end and has a diameter smaller than that of the second end.

A method for manufacturing a printed wiring board according to an aspect of the present case is a method for manufacturing the aforementioned printed wiring board, and includes: preparing a negative-type aforementioned photosensitive resin composition and a substrate, the photosensitive resin composition including: the aforementioned carboxyl group-containing resin (A), the aforementioned unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and the aforementioned photopolymerization initiator (C); the substrate has an insulating layer and the aforementioned second conductor layer stacked on the aforementioned insulating layer; The aforementioned second conductor layer is superimposed on the aforementioned substrate; after exposing the negative pattern-like region of the aforementioned coating film including the pattern of the aforementioned via hole, a development process is performed using an alkaline aqueous solution to form the aforementioned interlayer insulating layer and the aforementioned via hole penetrating the aforementioned interlayer insulating layer.

(1) Details of the problem to be solved Japanese Patent Laid-Open No. 2016-181731 discloses a method for manufacturing a multilayer printed circuit board, which includes: irradiating a carbon dioxide laser from a plastic film that has been made to adhere to the surface of an insulating layer containing more than 35% by mass of an inorganic filler material, and forming blind through holes with a top diameter of 100 μm or less. However, according to the technical idea of the present inventors, the invention described in Japanese Patent Application Laid-Open No. 2016-181731 still has room for improvement in the conduction reliability of the via hole. The conduction reliability of the tapered via hole tends to decrease.

The inventors of the present invention obtained the following technical idea through the research and development of the material of the interlayer insulating layer: cracks may occur in the conductor of the through-hole of the interlayer insulating layer, and this will deteriorate the conduction reliability.

Then, the inventors of the present invention completed the present project as a result of research and development in order to provide a printed wiring board having through-holes with high conduction reliability and a method of manufacturing the aforementioned printed wiring board.

(2) Summary One embodiment of this case will be described.

The printed circuit board 11 of this embodiment has: a first conductor layer 8; a second conductor layer 3; an interlayer insulating layer 7, which is interposed between the first conductor layer 8 and the second conductor layer 3; a through hole 6, which penetrates the interlayer insulating layer 7; and a via conductor 9, which is arranged in the through hole 6 and conducts the first conductor layer 8 and the second conductor layer 3 (refer to FIG. 1 E). The interlayer insulating layer 7 is a cured product of a negative photosensitive resin composition containing a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C). The through hole 6 has: a first end 61 which is an end on the first conductor layer 8 side; a second end 62 which is an end on the second conductor layer 3 side;

In this embodiment, the interlayer insulating layer 7 is fabricated from a negative-type photosensitive resin composition containing a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C). Therefore, the interlayer insulating layer 7 and the through hole 6 having the small-diameter portion 63 can be easily formed by exposing the film 4 made of the photosensitive resin composition in a pattern and then developing it with an alkaline aqueous solution.

The reason why it is easy to form the small-diameter portion 63 is presumed to be as follows. When light is irradiated on the surface of the first end 61 of the film 4 formed by the negative-type photosensitive resin composition to form the through hole 6 and the film 4 is exposed, the light will be scattered inside the film 4, and the closer to the deep part of the film 4, the easier it is to harden the wider part. Therefore, the non-cured portion 5 to be the through hole 6 gradually shrinks, and the small-diameter portion 63 having a diameter smaller than that of the first end 61 is easily formed. In addition, in the deeper side of the coating 4, light is absorbed by the coating 4, and the light is not easily transmitted, and therefore the influence of light scattering is reduced, so the hardening of the coating 4 is not easy, so the second end 62 has a smaller diameter.

In particular, when a film 4 with a film thickness of 5 μm to 100 μm is produced from a photosensitive resin composition, and ultraviolet rays having a spectral intensity at least one wavelength in the wavelength region of 365 nm±65 nm are irradiated on areas of the film 4 other than the circular portion with a diameter of 5 μm to 100 μm, and then the film 4 is subjected to development treatment by an alkaline aqueous solution, it is preferable that the photosensitive resin composition has the following characteristics: The circular portion forms the through hole 6 and the through hole 6 has a small diameter portion 63 . At this time, it is preferable that the diameter of the small-diameter portion 63 of the through hole 6 is 65% or more and less than 100% of the diameter of the second end 62, the diameter of the first end 61 is 65% or more of the diameter of the second end 62, and the diameter of the first end 61 is 100 μm or less. Such characteristics can be realized within the range of the composition of the photosensitive resin composition described in detail below. In addition, the method of irradiating ultraviolet rays to the film 4 may be an exposure method using a negative mask or a direct drawing method. Examples of specific test methods and conditions are described in the column of Examples.

In addition, in this embodiment, the via hole 6 has such a shape that even if a load due to heat is applied to the via hole conductor 9 and the like to generate stress in the via hole conductor 9, the interface between the via hole conductor 9 and the second conductor layer 3 is not easily cracked. Therefore, good conduction reliability of the interface between the first conductor layer 8 and the second conductor layer 3 can be easily obtained through the through holes. The reason for this is presumed to be that in the present embodiment, since the inner surface of the via hole 6 of the interlayer insulating layer 7 has a shape in which the diameter increases from the small diameter portion 63 to the second end 62, even if stress occurs in the via hole conductor 9, the stress is concentrated more at the small diameter portion 63 than at the second end 62 of the via hole.

The minimum diameter of the small-diameter portion 63 is preferably at least 65% and less than 100% of the diameter of the second end 62 . At this time, it is particularly easy to obtain the conduction reliability obtained by the via hole. The minimum diameter of the small-diameter portion 63 is preferably 95% or less of the diameter of the second end 62, more preferably 90% or less. In addition, the minimum diameter of the small-diameter portion 63 is preferably 67% or more of the diameter of the second end 62, and more preferably 79% or more.

Relative to the diameter of the second end 62, the diameter of the first end 61 is preferably more than 65%. At this time, the through-hole conductor 9 can be easily produced by infiltrating the plating solution into the through-hole 6 . In other words, through-hole conductor 9 can be easily produced by the plating method. Therefore, better conduction reliability is easily obtained. From the viewpoint of obtaining good resolution when forming the through hole 6 , the diameter of the first end 61 is preferably 70% or more, more preferably 75% or more, and most preferably 80% or more of the diameter of the second end 62 . In addition, relative to the diameter of the second end 62, the diameter of the first end 61 is preferably less than 130%, more preferably less than 120%, more preferably less than 110%, and most preferably less than 100%.

In addition, the diameter of the first end 61 is preferably less than 100 μm. In this case, the through-hole conductor 9 can be easily produced in the through-hole 6 by a plating method or the like. Therefore, better conduction reliability is easily obtained. In addition, the diameter of the first end 61 is, for example, 5 μm or more.

(3) Photosensitive resin composition The details of the photosensitive resin composition of the present embodiment will be specifically described below. In addition, in the following description, "(meth)acryl" means at least one of "acryl" and "methacryl". For example: (meth)acrylate means at least one of acrylate and methacrylate.

The photosensitive resin composition of the present embodiment contains a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C).

The carboxyl group-containing resin (A) preferably contains a carboxyl group-containing resin (A1) represented by the following formula (1) and having a bisphenol fennel skeleton. If the carboxyl group-containing resin (A) has a bulky bisphenol-skeleton skeleton, when ultraviolet rays are irradiated on the film 4 made of the photosensitive resin composition, light scattering is less likely to occur in the deep part. In addition, the carboxyl group-containing resin (A1) has a bisphenol peroxide skeleton, that is, can impart high heat resistance and insulation reliability to the cured product of the photosensitive resin composition.

In formula (1), R ₁ to R ₈ are each independently hydrogen, an alkyl group having 1 to 5 carbons, or halogen. In other words, in formula (1), R ₁ to R ₈ may each be hydrogen, an alkyl group having 1 to 5 carbons, or a halogen. The reason is that even if the hydrogen in the aromatic ring is replaced by a low-molecular-weight alkyl group or halogen, it will not adversely affect the physical properties of the carboxyl-containing resin (A1). On the contrary, the substitution may sometimes improve the heat resistance or flame retardancy of the cured product of the photosensitive resin composition containing the carboxyl-containing resin (A1).

The carboxyl group-containing resin (A1) is synthesized, for example, by reacting an epoxy compound (a1) having a bisphenol fluorine skeleton represented by formula (1) with an unsaturated group-containing carboxylic acid (a2), and then reacting the resulting intermediate with an acid anhydride (a3).

The epoxy compound (a1) has, for example, a structure represented by the following formula (2). In formula (2), n is an integer within the range of 0-20, for example. In order to appropriately control the molecular weight of the carboxyl group-containing resin (A1), the average of n is more preferably within the range of 0-1. When the average of n exists in the range of 0-1, it will become easy to suppress the excess molecular weight increase of carboxyl group-containing resin (A1). In addition, in formula (2), R ₁ to R ₈ are each independently hydrogen, an alkyl group having 1 to 5 carbons, or halogen.

The unsaturated group-containing carboxylic acid (a2) includes, for example, a compound having only one ethylenically unsaturated group in one molecule. More specifically, the unsaturated group-containing carboxylic acid (a2) contains, for example, at least one compound selected from the group consisting of acrylic acid, methacrylic acid, ω-carboxy-polycaprolactone (n≒2) monoacrylate, crotonic acid, cinnamic acid, 2-acryloxyethylsuccinic acid, 2-methacryloxyethylsuccinic acid, 2-acryloxyethylphthalic acid, 2-methacryloxyethylphthalic acid acid, 2-acryloxypropylphthalate, 2-methacryloxypropylphthalate, 2-acryloxyethylmaleic acid, 2-methacryloxyethylmaleic acid, β-carboxyethyl acrylate, 2-acryloxyethyltetrahydrophthalate, 2-methacryloxyethyltetrahydrophthalate, 2-acryloxyethylhexahydrophthalate, and 2- Methacryloxyethylhexahydrophthalic acid. Preferably, the unsaturated group-containing carboxylic acid (a2) contains acrylic acid. In addition, when the unsaturated group-containing carboxylic acid (a2) contains acrylic acid, the acrylic acid preferably contains 50 mol% or more of the unsaturated group-containing carboxylic acid (a2), more preferably contains 80 mol% or more, more preferably contains 85 mol% or more, particularly preferably contains 90 mol% or more.

When reacting the epoxy compound (a1) and the unsaturated group-containing carboxylic acid (a2), an appropriate method can be employed. For example: add the unsaturated group-containing carboxylic acid (a2) to the solvent solution of the epoxy compound (a1), and further add a thermal polymerization inhibitor and a catalyst as needed, and stir to obtain a reactive solution. The intermediate can be obtained by reacting the reactive solution at a temperature of preferably 60° C. to 150° C., particularly preferably 80° C. to 120° C., by a conventional method. In this case, the solvent can contain, for example, at least one component selected from the group consisting of: ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; acetates such as ethyl acetate, butyl acetate, celluloid acetate, butyl celluloid acetate, carbitol acetate, butyl carbitol acetate, and propylene glycol monomethyl ether acetate; and dialkyl glycol ethers. The thermal polymerization inhibitor can contain, for example, at least one component selected from the group consisting of hydroquinone, methylhydroquinone, and hydroquinone monomethyl ether. The catalyst can contain, for example, at least one component selected from the group consisting of: tertiary amines such as benzyldimethylamine and triethylamine; quaternary ammonium salts such as trimethylbenzylammonium chloride and methyltriethylammonium chloride; triphenylphosphine; and triphenylantimony.

Preferably the catalyst contains especially triphenylphosphine. In other words, it is preferred to react the epoxy compound (a1) with the unsaturated group-containing carboxylic acid (a2) in the presence of triphenylphosphine. At this time, the ring-opening addition reaction of the epoxy group in the epoxy compound (a1) and the unsaturated group-containing carboxylic acid (a2) can be particularly accelerated, and a reaction rate (conversion rate) of 95% or more, or 97% or more, or almost 100% can be achieved.

It is also preferred to react the epoxy compound (a1) with the unsaturated group-containing carboxylic acid (a2) under air bubbling. In this case, the addition polymerization reaction of the unsaturated group can be suppressed, and the increase in the molecular weight of the intermediate and the solution gelation of the intermediate can be suppressed. In addition, excessive coloring of the carboxyl group-containing resin (A1), which is the final product, can be suppressed.

When the epoxy compound (a1) is reacted with the unsaturated group-containing carboxylic acid (a2), the amount of the unsaturated group-containing carboxylic acid (a2) relative to 1 mol of the epoxy group of the epoxy compound (a1) is preferably 0.8 mol or more and 1.2 mol or less. In this case, a photosensitive resin composition having excellent photosensitivity and stability can be obtained.

The intermediate obtained as described above has a hydroxyl group generated by the reaction of the epoxy group of the epoxy compound (a1) and the carboxyl group of the unsaturated group-containing carboxylic acid (a2).

Then, the intermediate is reacted with an acid anhydride (a3). The acid anhydride (a3) contains, for example, an acid dianhydride (a4).

Acid dianhydride (a4) is a compound which has two acid anhydride groups. Acid dianhydride (a4) can contain the anhydride of tetracarboxylic acid. The acid dianhydride (a4) can contain, for example, at least one compound selected from the group consisting of 1,2,4,5-benzenetetracarboxylic dianhydride, benzophenone tetracarboxylic dianhydride, methylcyclohexene tetracarboxylic dianhydride, tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, 9,9'-bis(3,4-dicarboxyphenyl) terrene dianhydride, glycerol bis(trimellitate) anhydride) monoacetate, ethylene glycol bis(trimellitic acid anhydride), 3,3’,4,4’-diphenylenetetracarboxylic dianhydride, 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-diketonyl-3-furyl)naphtho[1,2-c]furan-1,3-dione, 1,2,3,4-butanetetracarboxylic dianhydride, and 3,3’,4,4’-bi Pyrellitic dianhydride. Particularly preferably, the acid dianhydride (a4) contains 3,3',4,4'-biphenyltetracarboxylic dianhydride. In this case, while the photosensitive resin composition ensures good developability, the stickiness of the film 4 made of the photosensitive resin composition can be suppressed, and the insulation reliability and plating resistance of the cured product can be further improved.

The acid anhydride (a3) may contain an acid monoanhydride (a5). Acid monoanhydride (a5) is a compound having one acid anhydride group. Acid monoanhydride (a5) can contain the anhydride of dicarboxylic acid. Acid monoanhydride (a5) can contain, for example, at least one compound selected from the group consisting of phthalic anhydride, 1,2,3,6-tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, succinic anhydride, methylsuccinic anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, cyclohexane-1,2,4- Triformic acid-1,2-anhydride, and itaconic anhydride. Particularly preferably, the acid monoanhydride (a5) contains 1,2,3,6-tetrahydrophthalic anhydride. In other words, it is preferable that the acid anhydride (a3) contains 1,2,3,6-tetrahydrophthalic anhydride. In this case, while ensuring good developability of the photosensitive resin composition, the stickiness of the film 4 formed of the photosensitive resin composition can be further suppressed, and the insulation reliability and plating resistance of the cured product can be further improved. The content of 1,2,3,6-tetrahydrophthalic anhydride is preferably in the range of 20 mol% to 100 mol%, more preferably 40 mol% to 100 mol%, but not limited thereto.

When reacting the intermediate with the acid anhydride (a3), an appropriate method can be employed. For example: add an acid anhydride (a3) to the solvent solution of the intermediate, and further add a thermal polymerization inhibitor and a catalyst as needed and stir and mix to obtain a reactive solution. The reactive solution is reacted at a temperature of preferably 60° C. to 150° C., particularly preferably 80° C. to 120° C., by a conventional method to obtain a carboxyl group-containing resin (A1) having a bisphenol fennel skeleton. Suitable solvents, catalysts, and polymerization inhibitors can be used, and the solvents, catalysts, and polymerization inhibitors used in the synthesis of intermediates can be used as they are.

Preferably the catalyst contains especially triphenylphosphine. In other words, it is preferred to react the intermediate with the acid anhydride (a3) in the presence of triphenylphosphine. In this case, the reaction between the intermediate and the acid anhydride (a3) is particularly accelerated, and a reaction rate (conversion rate) of 90% or more, 95% or more, 97% or more, or almost 100% can be achieved.

When the acid anhydride (a3) contains the acid dianhydride (a4), the amount of the acid dianhydride (a4) is preferably not less than 0.05 mol and not more than 0.24 mol relative to 1 mol of epoxy groups of the epoxy compound (a1). In this case, the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton with an appropriately adjusted acid value and molecular weight can be easily obtained.

When the acid anhydride (a3) further contains an acid anhydride (a5), the amount of the acid anhydride (a5) is preferably not less than 0.3 mol and not more than 0.7 mol relative to 1 mol of epoxy groups in the epoxy compound (a1). In this case, the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton with an appropriately adjusted acid value and molecular weight can be easily obtained.

It is also preferred to react the intermediate with the anhydride (a3) under air bubbles. In this case, excessive increase in the molecular weight of the carboxyl group-containing resin (A1) having a bisphenol terpene skeleton is suppressed, and the developability of the photosensitive resin composition by an aqueous alkaline solution is particularly improved.

Components other than the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton in the photosensitive resin composition will be described.

The photosensitive resin composition contains the carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and a photopolymerization initiator (C) as described above.

The carboxyl group-containing resin (A) may contain only the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton, or may contain only carboxyl group-containing resins other than the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton. Alternatively, both the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton and the carboxyl group-containing resin (A1) having a bisphenol fennel skeleton may be contained. Carboxyl group-containing resins other than the carboxyl group-containing resin (A1) having a bisphenol permeil skeleton include carboxyl group-containing resins (hereinafter also referred to as carboxyl group-containing resin (A2)) not having a bisphenol permeil skeleton.

The carboxyl group-containing resin (A2) can contain, for example, a compound (hereinafter referred to as (A2-1) component) which has a carboxyl group and does not have photopolymerization properties. (A2-1) The polymer which a component contains, for example 1 type of ethylenically unsaturated monomer containing the ethylenically unsaturated compound which has a carboxyl group. The ethylenically unsaturated compound having a carboxyl group can include compounds such as acrylic acid, methacrylic acid, and ω-carboxypolycaprolactone (n≒2) monoacrylate. The ethylenically unsaturated compound which has a carboxyl group can also contain the reactant with dibasic acid anhydride, such as pentaerythritol triacrylate and pentaerythritol trimethacrylate. Ethylenically unsaturated monomers may further include: 2-(meth)acryloxyethyl phthalate, 2-(meth)acryloxyethyl-2-hydroxyethyl phthalate, straight-chain or branched aliphatic or alicyclic (meth)acrylic acid esters that do not have carboxyl groups, etc.

The carboxyl group-containing resin (A2) may contain a compound (hereinafter referred to as (A2-2) component) having a carboxyl group and an ethylenically unsaturated group. In addition, the carboxyl group-containing resin (A2) may contain only the (A2-2) component. The component (A2-2) contains, for example, one kind of resin (referred to as the first resin (x)), which is a reaction product of a specific intermediate and at least one compound (x3) selected from the group of polycarboxylic acids and their anhydrides. The specific intermediate is a reaction product of an epoxy compound (x1) having two or more epoxy groups in one molecule and an ethylenically unsaturated compound (x2). The first resin (x) can be obtained, for example, by adding the compound (x3) to the intermediate obtained by reacting the epoxy group in the epoxy compound (x1) and the carboxyl group in the ethylenically unsaturated compound (x2) to obtain an intermediate. The epoxy compound (x1) can contain appropriate epoxy compounds such as a cresol novolak type epoxy compound, a phenol novolac type epoxy compound, and a biphenyl novolak type epoxy compound. In particular, the epoxy compound (x1) preferably contains at least one compound selected from the group consisting of biphenyl novolak-type epoxy compounds and cresol novolac-type epoxy compounds. The epoxy compound (x1) may contain only a biphenyl novolak-type epoxy compound, or may contain only a cresol novolak-type epoxy compound. In this case, since the main chain of the epoxy compound (x1) contains an aromatic ring, the degree to which the cured product of the photosensitive resin composition is significantly corroded by an oxidizing agent such as potassium permanganate can be reduced. The epoxy compound (x1) may contain a polymer of an ethylenically unsaturated compound (z). The ethylenically unsaturated compound (z) contains, for example, a compound (z1) having an epoxy group such as glycidyl (meth)acrylate, or a compound (z2) not having an epoxy group such as 2-(meth)acryloxyethyl phthalate. The ethylenically unsaturated compound (x2) preferably contains at least one of acrylic acid and methacrylic acid. The compound (x3) contains, for example, one or more compounds selected from the group consisting of polycarboxylic acids such as phthalic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid, and anhydrides of these polycarboxylic acids. In particular, the compound (x3) preferably contains at least one polyvalent carboxylic acid selected from the group of phthalic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid.

The component (A2-2) may contain a resin (referred to as a second resin (y)) which is a reaction product of a polymer of an ethylenically unsaturated monomer containing an ethylenically unsaturated compound having a carboxyl group and an ethylenically unsaturated compound having an epoxy group. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound not having a carboxyl group. The second resin (y) is obtained by reacting an ethylenically unsaturated compound having an epoxy group with a part of carboxyl groups in a polymer. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound not having a carboxyl group. The ethylenically unsaturated compound having a carboxyl group includes, for example, compounds such as acrylic acid, methacrylic acid, ω-carboxy-polycaprolactone (n≒2) monoacrylate, pentaerythritol triacrylate, and pentaerythritol trimethacrylate. Ethylenically unsaturated compounds without carboxyl groups include, for example: 2-(meth)acryloxyethyl phthalate, 2-(meth)acryloxyethyl-2-hydroxyethyl phthalate, straight-chain or branched aliphatic or alicyclic (only, a part of the ring may have an unsaturated bond) (meth)acrylic acid ester and other compounds. The ethylenically unsaturated compound having an epoxy group preferably contains glycidyl (meth)acrylate.

The carboxyl-containing resin (A) may contain only the carboxyl-containing resin (A1), only the carboxyl-containing resin (A2), or both the carboxyl-containing resin (A1) and the carboxyl-containing resin (A2). The carboxyl group-containing resin (A) preferably contains at least 25% by mass of the carboxyl group-containing resin (A1), more preferably at least 40% by mass, still more preferably at least 60% by mass, most preferably at least 100% by mass. In this case, the excellent photosensitivity of the photosensitive resin composition and the developability by alkaline aqueous solution can be ensured. Moreover, the heat resistance and insulation reliability of the hardened|cured material of a photosensitive resin composition can be improved especially. Furthermore, the stickiness of the film 4 formed of the photosensitive resin composition can be sufficiently reduced.

The weight average molecular weight of the carboxyl group-containing resin (A) is preferably 700 or more and 100,000 or less. If the weight average molecular weight of the carboxyl group-containing resin (A) is 700 or more, it is easy to suppress the stickiness of the film 4 formed by the photosensitive resin composition, and the insulation reliability and plating resistance of the cured product of the photosensitive resin composition can be improved. If the weight average molecular weight of the carboxyl group-containing resin (A) is 100,000 or less, the developability by the alkaline aqueous solution of the photosensitive resin composition will become favorable easily. The weight average molecular weight of the carboxyl group-containing resin (A) is preferably from 900 to 60,000, more preferably from 1,200 to 10,000, and particularly preferably from 1,400 to 5,000. The weight average molecular weight of the carboxyl group-containing resin (A) is calculated from the measurement results under the following conditions by gel permeation chromatography (GPC), for example.

GPC device: SHODEX SYSTEM 11 manufactured by Showa Denko; Column: Four series of SHODEX KF-800P, KF-005, KF-003, KF-001; Mobile phase: THF (tetrahydrofuran); Flow rate: 1 mL/min; Column temperature: 45°C; Detector: RI (refractive index); Conversion: polystyrene.

It is preferable that the carboxyl group-containing resin (A) contains the component whose acid value is 65 mgKOH/g or more and 150 mgKOH/g or less. In this case, the developability of the photosensitive resin composition by alkaline aqueous solution is particularly improved, and the exposed film 4 is developed by alkaline aqueous solution, that is, the through hole 6 having the small-diameter portion 63 can be produced particularly easily. More preferably, the acid value is not less than 70 mgKOH/g and not more than 145 mgKOH/g, still more preferably not less than 75 mgKOH/g and not more than 140 mgKOH/g, particularly preferably not less than 85 mgKOH/g and not more than 135 mgKOH/g.

The unsaturated compound (B) can impart photocurability to the photosensitive resin composition. The unsaturated compound (B) can contain, for example, at least one compound selected from the group consisting of monofunctional (meth)acrylates such as 2-hydroxyethyl (meth)acrylate; ) acrylate, ε-caprolactone modified pentaerythritol hexa(meth)acrylate, tricyclodecane dimethanol di(meth)acrylate and other multifunctional (meth)acrylates.

In particular, the unsaturated compound (B) is preferably a trifunctional compound, that is, a compound having three unsaturated bonds in one molecule. In this case, the resolution when exposing/developing the film 4 formed of the photosensitive resin composition is improved, and the developability of the photosensitive resin composition by an alkaline aqueous solution is particularly improved. The trifunctional compound can contain, for example, at least one compound selected from the group consisting of trimethylolpropane tri(meth)acrylate, EO (ethylene oxide) modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, ethoxylated isocyanurate tri(meth)acrylate, and ε-caprolactone modified ginseng(2-acryloxyethyl)isocyanurate, and ethoxylated glycerol tri(meth)acrylate.

It is also preferable that the unsaturated compound (B) contains a phosphorus-containing compound (phosphorus-containing unsaturated compound). In this case, the flame retardancy of the cured product of the photosensitive resin composition is improved. The phosphorus-containing unsaturated compound can contain, for example, at least one compound selected from the group consisting of: 2-methacryloxyethyl phosphate (specific examples are models LIGHT ESTER P-1M and LIGHT ESTER P-2M manufactured by Kyoeisha Chemical Co., Ltd.), 2-acryloxyethyl phosphate (a specific example is model LIGHT ACRYLATE P-1A manufactured by Kyoeisha Chemical Co., Ltd.), Specific examples are the model MR-260 manufactured by Daihachi Industry Co., Ltd.), and the HFA series manufactured by Showa Polymer Co., Ltd. (specific examples are: addition reactants of dipentaerythritol hexaacrylate and HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), namely models HFA-6003 and HFA-6007; caprolactone-modified dipentaerythritol hexaacrylate and HCA (9,10-dihydro-9-oxa -10-phosphaphenanthrene-10-oxide) addition reactants, namely model HFA-3003 and HFA-6127, etc.).

The unsaturated compound (B) may contain a prepolymer. The prepolymer can contain, for example, at least one compound selected from the group consisting of: a prepolymer obtained by polymerizing a monomer having an ethylenically unsaturated bond and adding an ethylenically unsaturated group; and oligo(meth)acrylate prepolymers. The oligomeric (meth)acrylate prepolymers can contain, for example, at least one component selected from the group consisting of epoxy (meth)acrylates, polyester (meth)acrylates, urethane (meth)acrylates, alkyd (meth)acrylates, silicone (meth)acrylates, and spirane resin (meth)acrylates.

The photopolymerization initiator (C) preferably contains a photopolymerization initiator (C1), and the photopolymerization initiator (C1) contains at least one selected from the group consisting of an acylphosphine oxide-based photopolymerization initiator, an α-aminoalkylphenone-based photopolymerization initiator, and an oxime ester-based photopolymerization initiator. At this time, when the photosensitive resin composition is exposed to ultraviolet rays, high light absorption can be imparted to the photosensitive resin composition. When the photosensitive resin composition has good light absorption, light is easily absorbed when exposing the coating film 4 formed of the photosensitive resin composition, so photocuring is easy to proceed. In addition, light is absorbed in the coating film 4, so that the amount of light reaching a deep part can be reduced. Therefore, the effect of light scattering is particularly difficult to occur in the deep part, and photocuring of the coating film 4 is more difficult to be performed in the deep part than in the surface. Therefore, when the through hole 6 is formed by photolithography, it is particularly easy to form the small-diameter portion 63 .

The photopolymerization initiator (C1) preferably contains an acylphosphine oxide-based photopolymerization initiator. In this case, higher light absorptivity can be provided to the photosensitive resin composition.

The acylphosphine oxide-based photopolymerization initiator can contain, for example, at least one component selected from the group consisting of: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoylethylphenylphosphinate and other monoacylphosphine oxide-based photopolymerization initiators; and bis(2,6-dichlorobenzoyl)phenylphosphine oxide, bis(2,6-dichlorobenzoyl)-2,5 -Dimethylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenylphosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthylphosphine oxide, bis(2,6-dimethoxybenzoyl)phenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2, Bisacylphosphine oxide-based photopolymerization initiators such as 5-dimethylphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and (2,5,6-trimethylbenzoyl)-2,4,4-trimethylpentylphosphine oxide. The acylphosphine oxide-based photopolymerization initiator more preferably contains at least one of 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and more preferably contains 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

The α-aminoalkylphenone-based photopolymerization initiator can contain, for example, at least one component selected from the group consisting of 2-methyl-1-(4-methylthiophenyl)-2-(N-morpholinyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-(N-morpholinyl)phenyl)butanone-1, 2-(dimethylamino)-2-[(4-methylphenyl)methyl]-1-[4-(4-morpholin Linyl)phenyl]-1-butanone.

The oxime ester photopolymerization initiator can contain, for example, at least one component selected from the group consisting of 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], ethyl ketone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-,1-(O-acetyl oxime).

The photoinitiator (C) may contain the photoinitiator (C2) containing the component other than the above other than the photoinitiator (C1) containing the said component. The photopolymerization initiator (C2) preferably contains at least one of α-hydroxyacetophenone-based photopolymerization initiators and thioxanthone-based photopolymerization initiators. In this case, particularly high light absorption can be imparted to the photosensitive resin composition. The photopolymerization initiator (C2) preferably contains an α-hydroxyacetophenone-based photopolymerization initiator.

The α-hydroxyacetophenone-based photopolymerization initiator preferably contains, for example, 1-hydroxycyclohexyl phenyl ketone 1-hydroxy cyclohexyl phenyl ketone.

The thioxanthone-based photopolymerization initiator preferably contains, for example, 2,4-diethylthioxanth-9-one.

Preferably, the photopolymerization initiator (C) contains 4,4-bis(diethylamino)benzophenone (C3). In other words, the photosensitive resin composition is also preferably: containing photopolymerization initiator (C1) and 4,4-bis(diethylamino)benzophenone (C3); or containing photopolymerization initiator (C1), photopolymerization initiator (C2) and 4,4-bis(diethylamino)benzophenone (C3). In this case, when developing after exposing a part of the coating film 4 formed of the photosensitive resin composition, it is easy to suppress hardening of the unexposed part especially. Therefore, it is particularly easy to form the through hole 6 having the small-diameter portion 63 .

4,4-bis(diethylamino)benzophenone (C3) is preferably in the range of 0.5 mass % or more and 20 mass % or less with respect to a photopolymerization initiator (C1). When 4,4-bis (diethylamino) benzophenone (C3) is 0.5 mass % or more, it becomes easy to suppress hardening of the unexposed part especially. When 4,4-bis(diethylamino)benzophenone (C3) is 20 mass % or less, 4,4-bis(diethylamino)benzophenone (C3) will not easily inhibit the electrical insulation of the hardened|cured material of a photosensitive resin composition. Bis(diethylamino)benzophenone (C3) is especially preferable in the range of 1 mass % or more and 18 mass % or less with respect to a photoinitiator (C1). When the photosensitive resin composition contains the organic filler (E), the organic filler (E) may cause light scattering in the photosensitive resin composition at the time of exposure. In this case, there is a possibility that a problem that good resolution cannot be obtained in the photosensitive resin composition may arise. Therefore, it may be difficult to form the small-diameter portion 63 in the through hole 6 . However, if the 4,4-bis(diethylamino)benzophenone (C3) is within the above range, the photosensitive resin composition tends to have good resolving power, and therefore it is particularly easy to form the small-diameter portion 63 in the through hole 6 .

The photosensitive resin composition preferably contains an epoxy resin (D). The epoxy resin (D) can impart thermosetting properties to the photosensitive resin composition. The epoxy resin (D) preferably contains a crystalline epoxy resin. In this case, the developability of the photosensitive resin composition can be improved. In addition, the epoxy resin (D) may further contain an amorphous epoxy resin. Here, a "crystalline epoxy resin" is an epoxy resin having a melting point, and an "amorphous epoxy resin" is an epoxy resin not having a melting point.

The crystalline epoxy resin preferably contains, for example, one or more components selected from the group consisting of 1,3,5-ginseng(2,3-epoxypropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, a hydroquinone type crystalline epoxy resin (a specific example is YDC-1312 manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), a biphenyl type crystalline epoxy resin (a specific example is Tris Ryo Chemical Co., Ltd., trade name YX-4000), diphenyl ether type crystalline epoxy resin (specific example, model YSLV-80DE manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), bisphenol type crystalline epoxy resin (specific examples, trade name YSLV-70XY and YSLV-80XY manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), tetraphenol ethane type crystalline epoxy resin (specific example, model G manufactured by Nippon Kayaku Co., Ltd. TR-1800), bisphenol fennel type crystalline epoxy resin.

The crystalline epoxy resin preferably has two or more epoxy groups in one molecule. In this case, it is possible to make the cured product of the photosensitive resin composition less likely to be cracked during repeated temperature changes.

The crystalline epoxy resin preferably has an epoxy equivalent of 150 g/eq or more and 300 g/eq or less. This epoxy equivalent is the g weight of the crystalline epoxy resin containing the epoxy group of 1 g equivalent. Crystalline epoxy resins have melting points. The melting point of the crystalline epoxy resin is, for example, not less than 70°C and not more than 180°C.

In particular, the epoxy compound (D) preferably contains a crystalline epoxy resin having a melting point of 110°C or lower. In this case, the developability by the alkaline aqueous solution of a photosensitive resin composition improves especially. The crystalline epoxy resin having a melting point of 110° C. or less can contain, for example, at least one component selected from the group consisting of biphenyl type epoxy resin (specific example is model YX-4000 manufactured by Mitsubishi Chemical Co., Ltd.), diphenyl ether type epoxy resin (specific example is model YSLV-80DE manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), and bisphenol type epoxy resin (specific example is model YSLV manufactured by NIPPON STEEL Chemical & Material Co., Ltd.) -70XY and YSLV-80XY), bisphenol peroxide type crystalline epoxy resin.

The amorphous epoxy resin preferably contains, for example, at least one component selected from the group consisting of: phenol novolac epoxy resin (a specific example is EPICLON N-775 manufactured by DIC Corporation), cresol novolac epoxy resin (a specific example is EPICLON N-695 manufactured by DIC Corporation), bisphenol A novolak epoxy resin (a specific example is EPICLON N-865 manufactured by DIC Corporation), bisphenol A epoxy Resin (specific example is model jER1001 manufactured by Mitsubishi Chemical Co., Ltd.), bisphenol F type epoxy resin (specific example is model jER4004P manufactured by Mitsubishi Chemical Co., Ltd.), bisphenol S type epoxy resin (specific example is model EPICLON EXA-1514 manufactured by DIC Co., Ltd.), bisphenol AD type epoxy resin, biphenol novolak type epoxy resin (specific example is model NC-3000 manufactured by Nippon Kayaku Co., Ltd.), hydrogenated bisphenol A type epoxy resin (specific example is NIPPON STEEL Chemical & Material Co., Ltd., model ST-4000D), naphthalene-type epoxy resin (specific example, DIC Co., Ltd., model EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770), tertiary butylcatechol-type epoxy resin (specific example, DIC Co., Ltd., model EPICLON HP-820), dicyclopentadiene-type epoxy resin (specific example, DIC Co., Ltd. Epiclon HP-7200 manufactured by the company), adamantane-type epoxy resin (specifically, model ADAMANTATEX-E-201 manufactured by Idemitsu Kosan Co., Ltd.), special bifunctional epoxy resin (specifically, model YL7175-500 and YL7175-1000 manufactured by Mitsubishi Chemical Co., Ltd.; model EPICLON TSR-960, EPICLON TER-601, EPICLON TSR manufactured by DIC Co., Ltd. -250-80BX, EPICLON 1650-75MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822, and EPICLON EXA-9726; model YSLV-120TE manufactured by NIPPON STEEL Chemical & Material Co., Ltd.), rubber-like core-shell polymer modified bisphenol A type epoxy resin (specifically, K Model MX-156 manufactured by ANEKA Co., Ltd.), rubber-like core-shell polymer modified bisphenol F-type epoxy resin (a specific example is model MX-136 manufactured by KANEKA Co., Ltd.), and bisphenol F-type epoxy resin containing rubber particles (a specific example is Kane Ace MX-130 manufactured by KANEKA Co., Ltd.).

When the photosensitive resin composition contains an epoxy resin (D), it is preferable that the photosensitive resin composition contains both a crystalline epoxy resin and an amorphous epoxy. In this case, the plating resistance and insulation properties of the cured product produced from the photosensitive resin composition can be further improved.

The epoxy resin (D) may contain a phosphorus-containing epoxy resin. In this case, the flame retardancy of the cured product of the photosensitive resin composition is improved. The phosphorus-containing epoxy resin may be contained in a crystalline epoxy resin, or may also be contained in an amorphous epoxy resin. Phosphorus-containing epoxy resins include, for example, phosphoric acid-modified bisphenol F-type epoxy resins (specific examples are models EPICLON EXA-9726 and EPICLON EXA-9710 manufactured by DIC Co., Ltd.), model Epotohto FX-305 manufactured by NIPPON STEEL Chemical & Material Co., Ltd., and the like.

The photosensitive resin composition preferably does not contain filler. In this case, light scattering in the deep portion of the coating 4 is suppressed, and the through-hole 6 having the small-diameter portion 63 is particularly easily formed. When the photosensitive resin composition contains a filler, it is preferable to appropriately set the material, particle size, and compounding amount of the filler so that light scattering is moderately less likely to occur in the coating film 4 .

The photosensitive resin composition may contain an organic filler (E). Furthermore, the organic filler (E) does not contain melamine. In this case, it is preferable to appropriately set the material, particle size, and compounding amount of the organic filler (E) as described above. The organic filler (E) imparts thixotropy to the photosensitive resin composition, and improves the storage stability of the photosensitive resin composition. In addition, the adhesion between the cured product and the plating layer improves. The organic filler (E) preferably has a reactive group. The organic filler (E) has a reactive group, has high compatibility in the photosensitive resin composition, and imparts stronger thixotropy to the photosensitive resin composition, and further improves the storage stability of the photosensitive resin composition. In addition, the adhesion between the cured product and the plating layer is further improved. The reactive groups of the organic filler (E) include, for example, more preferably at least one group selected from the group consisting of carboxyl, amine, epoxy, vinyl and hydroxyl, and more preferably at least one of carboxyl and amine. In this case, the storage stability of the photosensitive resin composition is further improved. In addition, the adhesion between the cured product and the plating layer is further improved. The reactive group that the organic filler (E) has particularly preferably contains a carboxyl group. In this case, the developability of the photosensitive resin composition will be improved. At the same time, the carboxyl group of the organic filler (E) can react with the epoxy resin (D) in the photosensitive resin composition during thermosetting. Thereby, the hardened|cured material after thermosetting can contain the organic filler (E) uniformly dispersed in the inside. In addition, it is also possible to modify the unreacted carboxyl group of the organic filler (E) in the step of roughening the surface of the cured product. In other words, among the organic fillers (E) contained in the cured product, the organic filler (E) located near the surface of the cured product tends to deteriorate in the step of roughening the surface of the cured product. The organic filler (E) modified as described above is easily removed from the cured product when roughening the cured product. Thereby, a rough surface can be given to the surface of a hardened|cured material, and the adhesiveness between a hardened|cured material and a plating layer can be improved. Furthermore, the organic filler (E) contains a carboxyl group, and can reduce the unevenness of the coating film originating in the fluidity of a photosensitive resin composition. Thereby, the film thickness of the layer formed from a photosensitive resin composition can be made uniform easily. In addition, it is easy to form the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 made of the photosensitive resin composition.

When the organic filler (E) contains a carboxyl group, the carboxyl group will form a side chain in the product by polymerizing or cross-linking carboxylic acid monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. The carboxylic acid monomer has a carboxyl group and a polymerizable unsaturated double bond. Since the organic filler (E) improves the thixotropy of the photosensitive resin composition, it improves the stability (especially storage stability) of the photosensitive resin composition. Moreover, when the organic filler (E) contains a carboxyl group, the developability of the cured product can be improved, and the compatibility of the crystalline epoxy resin can be improved to prevent crystallization in the photosensitive resin composition. The carboxyl group content of the organic filler (E) is not particularly limited, but the acid value of the organic filler (E) is preferably not less than 1 mgKOH/g and not more than 60 mgKOH/g in terms of the acid value obtained by acid-base titration. When the acid value is less than 1 mgKOH/g, the stability of the photosensitive resin composition and the developability of the cured product may decrease. When the acid value exceeds 60 mgKOH/g, the moisture resistance reliability of the cured product may decrease. The acid value of the organic filler (E) is preferably not less than 3 mgKOH/g and not more than 40 mgKOH/g.

The organic filler (E) preferably has an average primary particle diameter of 1 μm or less. The average primary particle diameter of the organic filler (E) is 1 μm or less, and the developability of the photosensitive resin composition is good. In addition, the roughness of the rough surface formed on the cured product can be reduced, and the anchoring effect can be increased as the surface area of the cured product increases, thereby improving the adhesion between the rough surface and the plating layer.

The lower limit of the average primary particle size of the organic filler (E) is not particularly limited, but is preferably at least 0.001 μm, for example. The average primary particle size is measured as D ₅₀ using a laser diffraction particle size distribution analyzer. More preferably, the average primary particle diameter of the organic filler (E1) is 0.4 μm or less, and more preferably 0.1 μm or less. In this case, light scattering in the photosensitive resin composition during exposure can be suppressed, thereby further improving the resolution of the photosensitive resin composition and making it easier to form the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 . In addition to this, the roughness of the rough surface formed on the cured product can be particularly finer.

The organic filler (E) is preferably dispersed in the photosensitive resin composition with a maximum particle size of less than 1.0 μm, more preferably less than 0.5 μm. The maximum particle diameter was measured as D ₅₀ using a laser diffraction particle size distribution analyzer. Alternatively, the maximum particle diameter is measured by observing the cured product using a transmission electron microscope (TEM). The organic filler (E) may aggregate in the photosensitive resin composition (for example, secondary particles may be formed), and in this case, the maximum particle diameter means the size of the aggregated particles. If the maximum particle size of the organic filler (E) in the dispersed state is within the above-mentioned range, scattering during exposure can be suppressed in the photosensitive resin composition, thereby further improving the resolution of the photosensitive resin composition, and forming the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 more easily. In addition, the roughness of the rough surface formed on the cured product can be made finer. Furthermore, when particle agglomeration occurs, the maximum particle size is usually larger than the average primary particle size.

The organic filler (E) preferably contains a rubber component. In addition, the organic filler (E) preferably contains only rubber components. The rubber component can impart flexibility to the cured product of the photosensitive resin composition. The rubber component can be constituted by resin. The rubber component preferably contains at least one polymer selected from crosslinked acrylic rubber, crosslinked nitrile rubber (NBR), crosslinked methyl methacrylate-butadiene-styrene (MBS), and crosslinked styrene-butadiene rubber (SBR). In this case, the rubber component can impart excellent flexibility to the cured product of the photosensitive resin composition. In addition, a more moderate roughness can be provided to the surface of the cured product. Here, the rubber component includes a crosslinked structure formed when copolymerization is performed using monomers constituting the polymer. Generally speaking, NBR is a copolymer of butadiene and acrylonitrile, which is classified as nitrile rubber. MBS is generally a copolymer composed of three components, methyl methacrylate, butadiene, and styrene, and is classified as a butadiene-based rubber. SBR is generally a copolymer of styrene and butadiene, and is classified as styrene rubber. Specific examples of the organic filler (E) include model XER-91-MEK manufactured by JSR Corporation, model XER-32-MEK manufactured by JSR Corporation, model XSK-500 manufactured by JSR Corporation, and the like. XER-91-MEK is a cross-linked rubber (NBR) having a carboxyl group with an average primary particle size of 0.07 μm, and it is provided as a methyl ethyl ketone dispersion containing 15% by weight of this cross-linked rubber, and its acid value is 10.0 mgKOH/g. XER-32-MEK is a dispersion obtained by dispersing a carboxyl group-modified hydrogenated nitrile rubber polymer (linear particles) in methyl ethyl ketone at a content of 17% by weight relative to the total amount of the dispersion. In addition, XSK-500 is a cross-linked rubber (SBR) having a carboxyl group and a hydroxyl group with an average primary particle diameter of 0.07 μm, and is provided as a methyl ethyl ketone dispersion containing 15% by weight of this cross-linked rubber. In this way, the organic filler (E) can be prepared as a dispersion liquid in the photosensitive resin composition. In other words, the rubber component can be formulated in the photosensitive resin composition as a dispersion liquid. In addition, specific examples of the organic filler (E) include, for example, model XER-92 made by JSR Co., Ltd., in addition to the above.

The photosensitive resin composition can contain a silane coupling agent. In this case, the dispersibility of the organic filler (E) can be improved. It is also possible to further improve the resolution of the photosensitive resin composition.

The silane coupling agent is, for example, a compound containing a silicon atom and 2 to 4 hydrolyzable groups selected from the group of —OCH ₃ groups, —OC ₂ H ₅ groups, and —OCOCH ₃ groups. In addition to the hydrolyzable groups, the silane coupling agent may also contain reactive groups such as amine groups, epoxy groups, vinyl (allyl), methacryl groups, mercapto groups, isocyanate groups, thioether groups, or methyl groups.

Examples of silane coupling agents include: 3-(2-aminoethylamino)propyldimethoxymethylsilane, 3-(2-aminoethylamino)propyltriethoxysilane, 3-(2-aminoethylamino)propyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane and other amino compounds; Silane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyl(dimethoxy)methylsilane, diethoxy(3-glycidoxypropyl)methylsilane and other epoxy compounds; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, -(meth)acrylic esters such as methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyldiethoxysilane; vinyl compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, diethoxymethylvinylsilane, vinyl ginseng (2-methoxyethoxy)silane; allyl compounds such as allyltriethoxysilane and allyltrimethoxysilane; p-styryltrimethoxy Styryl compounds such as silane; 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane and other isocyanates; Ethyl ester, methyltrimethoxysilane, etc.

The photosensitive resin composition can contain melamine. In this case, the degree to which the cured product of the photosensitive resin composition is significantly corroded by, for example, an oxidizing agent containing potassium permanganate can be reduced. In other words, the photosensitive resin composition contains melamine, and the thickness of the layer containing the cured product can be reduced when roughening the surface of the cured product of the photosensitive resin composition in the preceding step of the plating process. Roughening the surface of the cured product as described above can improve the adhesion between the cured product of the photosensitive resin composition and the plating layer composed of copper, gold, or the like. Melamine is 2,4,6-triamino-1,3,5-triazine, and can generally be obtained from a commercially available compound. Melamine is preferably dispersed in the photosensitive resin composition with an average particle size of 20 μm or less, preferably 15 μm or less. The melamine is uniformly dispersed in the photosensitive resin composition, and the melamine is more likely to carry out coordination bonding with metal elements. Thereby, the adhesiveness of a photosensitive resin composition can be improved more. The lower limit of the average particle diameter of melamine is not specifically limited, It can be 0.01 micrometer or more. In addition, the average particle diameter of melamine can be measured as _D50 using the laser diffraction particle size dispersion measuring apparatus in the state which disperse|distributed melamine in the uncured photosensitive resin composition.

The photosensitive resin composition may contain an inorganic filler. In this case, curing shrinkage of the film formed of the photosensitive resin composition is reduced. In addition, the dielectric loss tangent can be reduced. The inorganic filler can contain, for example, one or more materials selected from the group consisting of barium sulfate, silicon oxide, carbon nanotubes, talc, bentonite, aluminum hydroxide, magnesium hydroxide, and titanium oxide.

The photosensitive resin composition of this embodiment may contain an organic solvent. The organic solvent is used for the purposes of liquefaction or varnish of the photosensitive resin composition, viscosity adjustment, coating property adjustment, film-forming property adjustment, and the like.

The organic solvent can contain, for example, one or more compounds selected from the group consisting of: ethanol, propanol, isopropanol, hexanol, ethylene glycol and other linear, branched, secondary or polyhydric alcohols; methyl ethyl ketone, cyclohexanone and other ketones; toluene, xylene and other aromatic hydrocarbons; Celluloids such as celluloid; carbitol such as carbitol and butyl carbitol; propylene glycol alkyl ethers such as propylene glycol methyl ether; polypropylene glycol alkyl ethers such as dipropylene glycol methyl ether; acetates such as ethyl acetate, butyl acetate, celluloid acetate, and carbitol acetate; and dialkyl glycol ethers.

The carboxyl group-containing resin (A) is preferably in the range of 5% by mass to 85% by mass relative to the solid content of the photosensitive resin composition, more preferably in the range of 10% by mass to 75% by mass, and even more preferably in the range of 30% by mass to 60% by mass. In addition, the solid content means the total amount of all remaining components after removing volatile components, such as a solvent, from a photosensitive resin composition.

It is preferable that the unsaturated compound (B) which has at least one ethylenic unsaturated bond in 1 molecule exists in the range of 5 mass % or more and 45 mass % or less with respect to a carboxyl group containing resin (A). The unsaturated compound (B) is within this range, and it is particularly easy to produce the through-hole 6 having the small-diameter portion 63 . The unsaturated compound (B) is more preferably in the range of 10% by mass to 42% by mass based on the carboxyl group-containing resin (A), and more preferably in the range of 21% by mass to 40% by mass.

It is preferable that a photoinitiator (C) exists in the range of 1 mass % or more and 30 mass % or less with respect to a carboxyl group-containing resin (A). If the ratio of the photopolymerization initiator (C) is 1% by mass or more with respect to the carboxyl group-containing resin (A), the photosensitive resin composition will tend to have favorable light absorption. The photosensitive resin composition has good light absorption, easily increases the degree of hardening of the surface of the interlayer insulating layer 7 , and can reduce the water absorption of the interlayer insulating layer 7 . In addition, it is easier to form the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 . When the photopolymerization initiator (C) is 30% by mass or less with respect to the carboxyl group-containing resin (A), the cured film of the photosensitive resin composition will tend to have favorable electrical insulation.

With respect to the carboxyl group-containing resin (A), the photopolymerization initiator (C) is more preferably in the range of 1.5% by mass to 25% by mass, more preferably in the range of 2% by mass to 20% by mass, and particularly preferably in the range of 3% by mass to 10% by mass.

When the photosensitive resin composition contains the epoxy resin (D), it is preferable that the total of the equivalents of the epoxy groups contained in the epoxy resin (D) is 0.1 or more and 5 or less with respect to 1 equivalent of carboxyl groups of the carboxyl group-containing resin (A). The equivalent of the epoxy group of the epoxy resin (D) is 0.1 or more with respect to 1 equivalent of the carboxyl group of the carboxyl group-containing resin (A), that is, thermosetting properties can be imparted to the photosensitive resin composition. The equivalent weight of the epoxy group of the epoxy resin (D) is 5 or less with respect to 1 equivalent of carboxyl groups of the carboxyl group-containing resin (A), and the photosensitive resin composition has favorable developability. The equivalent weight of the epoxy group of the epoxy resin (D) is more preferably from 0.3 to 4, more preferably from 0.5 to 3, particularly preferably from 0.7 to 2, relative to 1 equivalent of carboxyl groups of the carboxyl group-containing resin (A).

The content of the organic filler (E) is preferably 1% by mass or more and 100% by mass or less with respect to the carboxyl group-containing resin (A). The content of the organic filler (E) is 1% by mass or more, and can appropriately roughen the surface of the cured product of the photosensitive resin composition, thereby improving the adhesion between the rough surface of the cured product and the plated surface. Content of an organic filler (E) is 100 mass % or less, and a photosensitive resin composition tends to have favorable developability. The content of the organic filler (E) relative to the carboxyl group-containing resin (A) is preferably from 1.5% by mass to 50% by mass, more preferably from 2% by mass to 30% by mass, and particularly preferably from 3% by mass to 20% by mass. In this case, it is particularly easy to fabricate the through hole 6 having the small-diameter portion 63 .

When the photosensitive resin composition contains a silane coupling agent, the content of the silane coupling agent is preferably not less than 0.01% by mass and not more than 7% by mass relative to the organic filler (E). When the ratio of the silane coupling agent is in this range, the aggregation of the organic filler (E) in the photosensitive resin composition is prevented, and the dispersibility is improved. The ratio of the silane coupling agent is preferably not less than 0.05% by mass and not more than 5% by mass relative to the organic filler (E). When the ratio of the silane coupling agent is in this range, the aggregation of the organic filler (E1) in the photosensitive resin composition can be prevented more efficiently, and the dispersibility can be improved more effectively.

When the photosensitive resin composition contains melamine, the content of melamine is preferably not less than 0.1% by mass and not more than 10% by mass based on the carboxyl group-containing resin (A). In this case, good developability is exhibited for an alkaline aqueous solution, and it is easier to form the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 . The content of melamine is preferably not less than 0.3% by mass and not more than 9% by mass, more preferably not less than 0.5% by mass and not more than 8% by mass, particularly preferably not less than 1% by mass and not more than 6% by mass, based on the carboxyl group-containing resin (A).

The ratio of the inorganic filler in the photosensitive resin composition is set appropriately, and the content of the inorganic filler is preferably 0 mass % or more and 200 mass % or less with respect to the carboxyl group-containing resin (A). In this case, good developability can be obtained, and it is easier to form the via hole 6 having the small-diameter portion 63 in the interlayer insulating layer 7 . Relative to the carboxyl group-containing resin (A), the content of the inorganic filler is preferably from 0% by mass to 150% by mass, more preferably from 0% by mass to 100% by mass, more preferably from 0% by mass to 50% by mass, and particularly preferably from 0% by mass to 20% by mass.

When the photosensitive resin composition contains an organic solvent, the amount of the organic solvent is preferably adjusted in the following manner: when the coating film formed by the photosensitive resin composition is dried, the organic solvent is quickly volatilized, that is, the organic solvent does not remain in the dried film. In particular, the proportion of the organic solvent is preferably from 0 mass % to 99.5 mass % with respect to the entire photosensitive resin composition, and more preferably from 15 mass % to 60 mass %. In addition, since the suitable ratio of an organic solvent differs with a coating method etc., it is preferable to adjust a ratio suitably according to a coating method.

The photosensitive composition may further contain components other than the above components as long as the effects of the present embodiment are not inhibited.

The photosensitive resin composition may contain at least one resin selected from the group consisting of: toluene diisocyanate, morpholine diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate blocked with caprolactam, oxime, malonate, etc.; butylated urea resin; various thermosetting resins other than the above; ultraviolet curable epoxy (meth)acrylate; Type A, phenol novolak type, cresol novolak type, alicyclic type and other epoxy resins; and diallyl phthalate resin, phenoxy resin, urethane resin, melamine resin, fluorine resin and other polymer compounds.

The photosensitive resin composition may contain a curing agent for curing the epoxy compound (D). The hardener can contain, for example, at least one component selected from the group consisting of imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 4-phenylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-(2-cyanoethyl)-2-ethyl-4-methylimidazole and other imidazole derivatives; dicyandiamide, benzyldimethylamine, 4-(dimethylamino)-N,N-dimethyl Amine compounds such as benzylamine, 4-methoxy-N,N-dimethylbenzylamine, and 4-methyl-N,N-dimethylbenzylamine; hydrazine compounds such as adipic hydrazine and sebacyl hydrazine; phosphorus compounds such as triphenylphosphine; acid anhydrides; phenols; mercaptans; Lewis acid amine complexes; and onium salts. Commercial products of these components are, for example: 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (all are trade names of imidazole compounds) manufactured by Shikoku Chemical Co., Ltd.; U-CAT3503N and U-CAT3502T (all are trade names of dimethylamine-blocked isocyanate compounds) manufactured by San-Apro Co., Ltd.; DBU, DBN, U-CATSA102, U-CAT5 002 (both are bicyclic amidine (amidine) compounds and their salts).

The photosensitive resin composition may contain an adhesiveness imparting agent. Adhesion imparting agents include, for example: guanamine derivatives such as acetoguanamine (2,4-diamino-6-methyl-1,3,5-triazine) and benzoguanamine (2,4-diamino-6-phenyl-1,3,5-triazine); S-triazine derivatives such as S-triazine, 2-vinyl-4,6-diamino-S-triazine・isocyanuric acid adduct, 2,4-diamino-6-methacryloxyethyl-S-triazine・isocyanuric acid adduct, etc. S-triazine derivatives; silane coupling agent; melamine derivatives, etc.

The photosensitive resin composition may contain a rheology control agent. The viscosity of the photosensitive resin composition can be easily adjusted by the rheology control agent. The rheology control agent can be exemplified for example: urea-modified mid-polar polyamide (model BYK-430, BYK-431 produced by BYK Japan Co., Ltd.), polyhydroxycarboxamide (model BYK-405 produced by BYK Japan Co., Ltd.), modified urea (model BYK-410, BYK-411, BYK-420 produced by BYK Japan Co., Ltd.), polymer urea derivatives ( BYK Japan Co., Ltd. model BYK-415), urea modified urethane (BYK Japan Co., Ltd. model BYK-425), polyurethane (BYK Japan Co., Ltd. model BYK-428), castor oil wax, polyethylene wax, polyamide wax, bentonite, kaolin, clay.

The photosensitive resin composition may contain at least one component selected from the group consisting of: hardening accelerator; colorant; copolymers such as silicon oxide and acrylate; leveling agent; thixotropic agent; polymerization inhibitor; antihalation agent; flame retardant; defoamer; antioxidant; surfactant;

What is necessary is just to adjust by an appropriate method when preparing the photosensitive resin composition of this embodiment. For example, the photosensitive resin composition can be adjusted by mixing and stirring the raw materials of the photosensitive resin composition. In addition, the photosensitive resin composition can also be prepared, for example, by kneading by an appropriate kneading method using a three-roll mill, a ball mill, a sand mill, or the like. When the raw materials contain liquid components, low-viscosity components, etc., the photosensitive resin composition can be prepared by first kneading parts of the raw materials other than the liquid components, low-viscosity components, etc. to prepare a mixture, and then adding the liquid components, low-viscosity components, etc. to the obtained mixture and mixing. When the photosensitive resin composition contains the solvent (E), first, after mixing a part or all of the solvent among the raw materials, it is mixed with the remaining raw materials.

The photosensitive resin composition preferably has a property that it can be developed with a sodium carbonate aqueous solution even if it is the film 4 with a thickness of 25 μm. At this time, since a sufficiently thick electrically insulating layer can be produced from the photosensitive resin composition by photolithography, the photosensitive resin composition can be widely used to produce the interlayer insulating layer 7 in the printed wiring board 11 . Of course, an electrically insulating layer thinner than a thickness of 25 μm can also be produced from a photosensitive resin composition.

Whether or not the film 4 with a thickness of 25 μm can be developed with an aqueous sodium carbonate solution can be confirmed by the following method. A photosensitive resin composition was applied on a suitable substrate 1 to form a wet coating film, and the wet coating film was heated at 80° C. for 40 minutes to form a film 4 with a thickness of 25 μm. In the state where the negative mask is directly attached to the film 4, ultraviolet rays are irradiated on the film 4 under the condition of 500 mJ/cm ² for exposure. After the exposure, the film 4 was treated by spraying a 1% Na ₂ CO ₃ aqueous solution at 30° C. for 90 seconds at a spray pressure of 0.2 MPa, and then spraying pure water for 90 seconds at a spray pressure of 0.2 MPa. When the film 4 was observed after this treatment, the portion corresponding to the non-exposed portion of the film 4 was removed and no residue was confirmed. At this time, it can be judged that the film 4 with a thickness of 25 μm can be developed with an aqueous solution of sodium carbonate. Furthermore, it can also be confirmed whether or not it can be developed with a sodium carbonate aqueous solution for a film 4 of other thickness (for example, 30 μm).

(2.2) Manufacture of printed wiring board 11 The method of manufacturing the printed wiring board 11 of this embodiment will be described in detail with reference to FIGS. 1A to 1E.

When manufacturing the printed wiring board 11, for example, a photosensitive resin composition and a substrate are prepared. The substrate has an insulating layer 2 and a second conductor layer 3 stacked on the insulating layer 2 . A coating film 4 made of a photosensitive resin composition is superimposed on the substrate so as to cover the second conductor layer 3, and after exposing the negative pattern-shaped region of the coating film 4 including the pattern of the through hole 6, a development treatment is performed using an alkaline aqueous solution. Thereby, the interlayer insulating layer 7 and the via hole 6 penetrating the interlayer insulating layer 7 are formed.

Specifically, for example, first, a substrate 1 is prepared as shown in FIG. 1A . The substrate 1 includes an insulating layer 2 and a second conductor layer 3 . The second conductor layer 3 is a conductor line.

The photosensitive resin composition is applied on the substrate, and further dried as necessary to prepare the film 4 covering the second conductor layer 3 as shown in FIG. 1B. The coating method of the photosensitive resin composition is selected from the group consisting of known methods such as dipping, spraying, spin coating, roll coating, curtain coating and screen printing. When drying the photosensitive resin composition, the photosensitive resin composition is heated at a temperature of, for example, 60° C. or higher and 130° C. or lower.

The film 4 can also be produced by overlaying a dry film made of a photosensitive resin composition on a substrate. The dry film is, for example, formed on a support by applying a photosensitive resin composition on an appropriate support made of polyester or the like and drying it. Thereby, a dry film with a support is obtained, which comprises: a dry film and a support for supporting the dry film. After the dry film of the dry film with a support was laminated on the substrate 1 so as to cover the second conductor layer 3 , pressure was applied to the dry film and the substrate 1 . Thereby, the coating film 4 made of a dry film is superimposed on the base material 1 .

Then, the film 4 is exposed. For example, exposure is performed on a negative pattern region of the film 4 including the pattern of the through hole 6 . At this time, for example, the coating 4 is irradiated with ultraviolet rays via a negative mask. The negative mask includes: an exposed portion through which ultraviolet rays can pass; and a non-exposed portion capable of shielding ultraviolet rays, and the pattern of the non-exposed portion includes the pattern of the through hole 6 . A negative mask is a photo tool such as a mask film, a dry plate, or the like. The light source of ultraviolet rays is, for example, selected from the group consisting of chemical lamps, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, and metal halide lamps.

When producing the film 4 from a dry film, when exposing the film 4 , for example, after peeling the support body from the film 4 in advance, the film 4 is exposed. In addition, the film 4 may be exposed by directly penetrating the support with ultraviolet rays irradiating the film 4 in a state where the support is superimposed on the film 4 , and then the support may be peeled off from the exposed film 4 .

As the exposure method, methods other than the method using a negative mask may be used. The film 4 can be exposed, for example, by a direct drawing method in which only the portion of the film 4 to be exposed is irradiated with ultraviolet light emitted from a light source. The light source used in the direct drawing method is, for example, selected from the group consisting of high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, g-lines (436 nm), h-lines (405 nm), i-lines (365 nm), and combinations of two or more of g-lines, h-lines, and i-lines.

The ultraviolet ray irradiated on the coating 4 preferably has a spectral intensity in at least one wavelength in the wavelength region of 365 nm±65 nm. In addition, it is preferable that the ultraviolet rays irradiated on the film 4 have no spectral intensity at a wavelength of 435 nm or more. The ultraviolet rays irradiated on the coating 4 have spectral intensity in at least one wavelength in the wavelength region of 365 nm±65 nm, and hardening of the coating 4 is facilitated. In addition, if the ultraviolet light includes light having a wavelength of 435 nm or more, the diameter of the second end 62 of the via hole 6 formed in the interlayer insulating layer 7 is likely to be reduced after development. The reason for this is presumed to be that long-wavelength light of 435 nm or more is not easily absorbed by the photosensitive resin composition, so it is easy to propagate to the deep part of the film 4, and light scattering is likely to occur in the deep part of the film 4. The ultraviolet ray irradiated on the coating 4 is more preferably at least one wavelength in the wavelength region of 365 nm±45 nm has spectral intensity and does not have spectral intensity above 415 nm, more preferably at least one wavelength in the wavelength region of 365 nm±30 nm has spectral intensity and does not have spectral intensity above 400 nm, and is particularly preferably at least one wavelength in the wavelength region of 365 nm±15 nm has spectral intensity and does not have spectral intensity above 385 nm .

Then, the film 4 is developed with an alkaline aqueous solution to form the interlayer insulating layer 7 having the through holes 6 . At this time, as described above, it is easy to form the through hole 6 having the small-diameter portion 63 . The film 4 is subjected to developing treatment to remove the non-hardened portion 5 of the film 4 shown in FIG. 1C , thereby forming the through hole 6 as shown in FIG. 1D . An appropriate developer can be used in the development process according to the composition of the photosensitive resin composition. The developing solution is, for example, an alkaline aqueous solution or an organic amine, and the alkaline aqueous solution contains at least one of an alkali metal salt and an alkali metal hydroxide. More specifically, the alkaline aqueous solution contains, for example, at least one component selected from the group consisting of sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, ammonium hydrogencarbonate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, and lithium hydroxide. The solvent in the alkaline aqueous solution may be only water, or a mixture of water and hydrophilic organic solvents such as lower alcohols. The organic amine contains, for example, at least one component selected from the group consisting of monoethanolamine, diethanolamine, triethanolamine, monoisopropanolamine, diisopropanolamine, and triisopropanolamine.

The alkaline aqueous solution preferably contains at least one of an alkali metal salt and an alkali metal hydroxide, and particularly preferably contains sodium carbonate. In this case, it is possible to improve the working environment and reduce the burden of waste disposal.

Since the photosensitive resin composition of this embodiment has good developability, residues of the uncured photosensitive resin composition after development are less likely to remain on the bottom of the through hole 6 . Therefore, it is easy to form the through hole 6 having the small diameter portion 63 .

Then, the film 4 after the development can be heated and thermally cured. The heating conditions are, for example, a heating temperature in the range of 120° C. to 200° C., and a heating time in the range of 20 minutes to 180 minutes. If the film 4 is thermally cured in the above-mentioned manner, the performance such as strength, hardness, and chemical resistance of the interlayer insulating layer 7 will be improved.

The film 4 may be further irradiated with ultraviolet rays before heating and after heating, or both, as required. In this case, photocuring of the coating film 4 can be further advanced.

As a result, the interlayer insulating layer 7 made of a cured photosensitive resin composition can be provided on the substrate 1 . Then, the first conductor layer 8 , which is the conductor line, can be formed on the interlayer insulating layer 7 by a conventional method such as an additive method, and the through-hole conductor 9 can be formed in the through hole 6 . Thereby, printed wiring board 11 including first conductor layer 8 , second conductor layer 3 , interlayer insulating layer 7 , via hole 6 , and via hole conductor 9 as shown in FIG. 1E can be obtained. In addition, although the via-hole conductor 9 is filled in the whole inside of the via-hole 6 in FIG. 1E, the via-hole conductor 9 may be the film which covers the inner surface of the via-hole 6.

In addition, the entire inner surface of the via hole 6 and a part of the outer surface of the interlayer insulating layer 7 may be roughened before forming the via-hole conductor 9 . In this case, the adhesiveness between base material 1 and via-hole conductor 9 can be improved.

The roughening of a part of the outer surface of the interlayer insulating layer 7 and the entire inner surface of the via hole 6 can be performed in the same procedure as the general desmear treatment using an oxidizing agent. For example, the outer surface of the interlayer insulating layer 7 is roughened by bringing an oxidizing agent into contact with the outer surface of the interlayer insulating layer 7 . However, it is not limited thereto, and appropriate roughening methods such as plasma treatment, UV (ultraviolet) treatment, and ozone treatment may also be employed.

The oxidizing agent may be an oxidizing agent available as a desmear solution. Such an oxidizing agent can contain, for example, at least one permanganate selected from the group of sodium permanganate and potassium permanganate.

When the through-hole conductor 9 is provided, an initial conductor can be formed by performing electroless metal plating on a part of the roughened outer surface and the inner surface of the through hole 6 . Then, the metal in the electrolytic plating solution is deposited on the initial conductor by electrolytic metal plating, that is, the via-hole conductor 9 can be formed. [Example]

The present case is specifically described below by means of examples. However, this case is not limited by the following embodiments, as long as the purpose of this case can be achieved, various changes can be made according to the design.

1. Synthesis of carboxyl-containing resins [Synthesis Examples 1 to 6: Resins containing a bisphenol peroxide skeleton] In a four-necked flask equipped with a reflux cooler, a thermometer, an air blowing tube, and a stirrer, the ingredients indicated in the "First Reaction" column in Table 1 were added, and these were stirred under air bubbling to prepare a mixture. This mixture was heated in the flask under the reaction temperature and reaction time shown in the column of "reaction conditions" while stirring under air bubbling. Thereby, the solution of the intermediate body was prepared.

Then, into the solution of the intermediate in the flask, the components shown in the "Second Reaction" column of Table 1 were added, and while stirring under air bubbling, the mixture was heated at the reaction temperature and reaction time shown in the "Reaction Condition (1)" column. Then, while stirring under air bubbling, it heated at the reaction temperature and reaction time shown in the column of "reaction conditions (2)". Thereby, a 65% by mass solution of a carboxyl group-containing resin was obtained. The weight average molecular weight and acid value of the carboxyl group-containing resin are as shown in Table 1.

In addition, the detail of the component shown in the (a1) column in Table 1 is as follows. - Epoxy compound 1: a bisphenol fluorine-type epoxy compound represented by formula (2), wherein R ₁ to R ₈ in formula (2) are all hydrogen, and has an epoxy equivalent of 250 g/eq.・Epoxy compound 2: a bisphenol fluorine-type epoxy compound represented by formula (2), in which R ₁ and R ₅ are both methyl groups, and R ₂ to R ₄ and R ₆ to R ₈ are all hydrogen, and have an epoxy equivalent of 279 g/eq.

[Synthesis Example 7: Resin Containing Biphenyl Novolak Skeleton] In a four-necked flask equipped with a reflux cooler, a thermometer, an air blowing pipe, and a stirrer, 288 parts by mass of a biphenyl novolak-type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., model NC-3000-H, epoxy equivalent 288 g/eq), 155 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 parts by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine were added to prepare a mixture. The mixture was heated in a flask at a temperature of 115° C. for 12 hours while stirring under air bubbling. Thereby, the solution of the intermediate body was prepared.

Then, 85 parts by mass of tetrahydrophthalic anhydride and 86.3 parts by mass of diethylene glycol monoethyl ether acetate were added to the solution of the intermediate in the flask, and heated at 90° C. for 4 hours while stirring under air bubbling. Thereby, a 65% by mass solution of carboxyl group-containing resin B-1 was obtained. The weight average molecular weight of the carboxyl group-containing resin B-1 was 8026, and the acid value was 69 mgKOH/g.

2. Modulation of composition After kneading the components shown in Tables 2 to 3 described later using a three-roll mill, they were stirred and mixed in a flask to obtain a composition. In addition, the details of the components shown in Tables 2-3 are as follows. ・Unsaturated compound A: trimethylolpropane triacrylate. - Photopolymerization initiator A: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, manufactured by BASF Corporation, model Irgacure TPO. - Photopolymerization initiator B: 1-hydroxycyclohexyl phenyl ketone, manufactured by BASF Corporation, model Irgacure 184. ・Photopolymerization initiator C: 4,4'-bis(diethylamino)benzophenone. ・Photopolymerization initiator D: 2,4-diethylthioxanthen-9-one. ・Crystalline epoxy resin A: bisphenol type crystalline epoxy resin, model YSLV-80XY manufactured by NIPPON STEEL Chemical & Material Co., Ltd., melting point 75-85° C., epoxy equivalent 192 g/eq. ・Amorphous epoxy resin solution A: A solution obtained by dissolving bisphenol A type epoxy resin containing long carbon chains, manufactured by DIC Co., Ltd., model EPICLON EXA-4816, liquid resin, epoxy equivalent 410 g/eq, in diethylene glycol monoethyl acetate at a solid content of 90%. ・Dispersion of organic filler A: a dispersion obtained by dispersing cross-linked rubber (NBR) with an average primary particle diameter of 0.07 μm in methyl ethyl ketone at a content of 15% by weight relative to the total amount of the dispersion (manufactured by JSR Co., Ltd., model XER-91-MEK; acid value: 10.0 mgKOH/g). ・Organic filler B: Glycidyl-modified acrylonitrile butadiene rubber with an average primary particle size of 0.3 μm. ・Additive A: 3-glycidoxypropyltrimethoxysilane. ・Additive B: Melamine. ・Solvent A: methyl ethyl ketone.

3. Evaluation of composition (1) Preparation of test piece Using the composition of each composition example, the test piece was produced as follows.

The composition of each composition example was coated on a polyethylene terephthalate film using an applicator, heated at 80° C. for 5 minutes, and then dried at 95° C. for 20 minutes to form a dry film with a thickness of 35 μm on the film.

A glass-epoxy copper-clad laminate (FR-4 type) having a copper foil with a thickness of 17.5 μm was prepared. The surface portion of the glass-epoxy copper-clad laminate with a thickness of about 1 μm was treated with an etchant (model CZ-8101 manufactured by MEC Co., Ltd.) to roughen it. A vacuum lamination machine was used to heat-laminate the above-mentioned dry film on one side of the glass-epoxy copper-clad laminate. The conditions for heating lamination were set to 0.5 MPa, 80° C., and 1 minute. Thereby, the coating film which consists of the said dry film was formed on the glass epoxy copper-clad laminated board. Ultraviolet rays with a wavelength of 365 nm were irradiated to the film at a cumulative light intensity of 250 mJ/cm ² through a negative mask having a non-exposed portion of a circular pattern with a diameter of 80 μm and a polyethylene terephthalate film. Then, the polyethylene terephthalate film was peeled off from the film.

Then, the film was developed by spraying a 30° C. alkaline aqueous solution (1% Na ₂ CO ₃ aqueous solution) at a spray pressure of 0.2 MPa for 90 seconds, and then spraying pure water at a spray pressure of 0.2 MPa for 90 seconds. Then, the film was heated at 180° C. for 120 minutes. Thereby, an interlayer insulating layer and a through hole penetrating the interlayer insulating layer are formed on the printed circuit board. Thereby, a test piece was obtained.

The following evaluations were performed on this test piece. In addition, in composition example 11, development was not possible, and evaluation was not performed. In addition, in Composition Example 14, evaluation was not performed because there was a position where film peeling due to insufficient curing was observed during development.

(2) Determination of the diameter of the first end and the diameter of the second end The test piece was cut so as to bisect the through-hole on a plane parallel to the axis of the through-hole, and the cross-section was photographed using an electron microscope (SEM). From the images thus obtained, the diameter of the first end and the diameter of the second end of the through hole were determined. In addition, the value of (diameter of the first end÷diameter of the second end)×100(%) was obtained.

(3) Presence of small diameter part From the images obtained in the above "(2) Measurement of the diameter of the first end and the diameter of the second end", whether there is a small-diameter portion between the first end and the second end of the through hole was confirmed, and evaluated in the following manner. A: A small-diameter portion exists between the first end and the second end, and the minimum diameter of the small-diameter portion is 65% or more and less than 100% of the diameter of the second end. B: A small-diameter portion exists between the first end and the second end, and the minimum diameter of the small-diameter portion is less than 65% of the diameter of the second end. C: The small-diameter portion does not exist between the first end and the second end.

(4) Evaluation of via hole shape From the images obtained in the above "(2) Measurement of the diameter of the first end and the diameter of the second end", the shape of the through-hole was evaluated in the following manner. A: The value of (diameter of the first end÷diameter of the second end)×100(%) is 80% or more, and there is a small-diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. B: The value of (diameter of the first end÷diameter of the second end)×100(%) is 75% or more and less than 80%, and there is a small diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. C: The value of (diameter of the first end÷diameter of the second end)×100(%) is 65% or more and less than 75%, and there is a small diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. D: The value of (diameter of the first end÷diameter of the second end)×100(%) is less than 65%, and a small-diameter portion exists between the first end and the second end. E: There is no small-diameter portion.

The results of the evaluation tests described above are shown in Tables 2 to 3 below.

4. Evaluation of printed circuit boards (1) Preparation of test piece Test pieces were produced by the method described in "(1) Preparation of test pieces" in "1. Evaluation of composition" above, except that the method of forming the film and the thickness of the film at the time of film production, the diameter of the circular pattern at the time of exposure, the wavelength of ultraviolet light and the integrated light intensity, and the spraying time of the alkaline aqueous solution at the time of development were as shown in Tables 4 to 6. In addition, when plural numerical values are described in the column of the wavelength, the ultraviolet rays having the wavelengths of the respective numerical values are irradiated simultaneously.

The following evaluations were performed on this test piece. In addition, in the comparative example 1, image development was not possible, and evaluation was not performed. In addition, in Comparative Example 3, evaluation was not performed because there was a position where film peeling due to insufficient curing was observed during image development.

(2) Determination of the diameter of the first end and the diameter of the second end The test piece was cut so as to bisect the through hole on a plane parallel to the axis of the through hole, and the cross section was observed using an electron microscope (SEM). From the images thus obtained, the diameter of the first end and the diameter of the second end of the through hole were determined. In addition, the value of (diameter of the first end÷diameter of the second end)×100(%) was obtained.

(3) Presence of small diameter part From the images obtained in the above "(2) Measurement of the diameter of the first end and the diameter of the second end", whether there is a small-diameter portion between the first end and the second end of the through hole was confirmed, and evaluated in the following manner. A: A small-diameter portion exists between the first end and the second end, and the minimum diameter of the small-diameter portion is 65% or more and less than 100% of the diameter of the second end. B: A small-diameter portion exists between the first end and the second end, and the minimum diameter of the small-diameter portion is less than 65% of the diameter of the second end. C: The small-diameter portion does not exist between the first end and the second end.

(4) Evaluation of via hole shape From the images obtained in the above "(2) Measurement of the diameter of the first end and the diameter of the second end", the shape of the through-hole was evaluated in the following manner. A: The value of (diameter of the first end÷diameter of the second end)×100(%) is 80% or more, and there is a small-diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. B: The value of (diameter of the first end÷diameter of the second end)×100(%) is 75% or more and less than 80%, and there is a small diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. C: The value of (diameter of the first end÷diameter of the second end)×100(%) is 65% or more and less than 75%, and there is a small diameter portion between the first end and the second end with a diameter of 65% or more and less than 100% of the diameter of the second end. D: The value of (diameter of the first end÷diameter of the second end)×100(%) is less than 65%, and a small-diameter portion exists between the first end and the second end. E: There is no small-diameter portion.

(5) Through-hole connection reliability For the test piece, the outer surface of the interlayer insulating layer was roughened by the following general desmear treatment as a step before the plating treatment.

The interlayer insulating layer was subjected to swelling treatment at 70° C. for 10 minutes using a swelling solution for desmearing (Swelling Dip Securiganth P manufactured by Atotech Japan Co., Ltd.) to swell the surface of the interlayer insulating layer, and then the interlayer insulating layer was washed with hot water. Then, the surface of the interlayer insulating layer was roughened by treatment with a desmear solution (an oxidizing agent containing potassium permanganate, Concentrate Compact CP manufactured by Atotech Japan Co., Ltd.) at 70° C. for 10 minutes, and then the interlayer insulating layer was washed with hot water. Then, the surface of the interlayer insulating layer was treated with a neutralizing solution (Reduction Securiganth P manufactured by Atotech Japan Co., Ltd.) at 40° C. for 5 minutes to remove residues, and then the interlayer insulating layer was washed with water.

Then, electroless copper plating was performed on the interlayer insulating layer to form an initial conductor, followed by heating at 150° C. for 1 hour. Then, electrolytic copper plating was performed on the primary conductor under the condition of a current density of 2 A/dm ² , and then heated at 180° C. for 30 minutes. Thereby, a first conductor layer having a thickness of 33 μm was formed on the interlayer insulating layer, and via conductors were formed in the via holes.

Then, the test piece was subjected to a temperature cycle test in which a cycle of exposing to a condition of −55° C. for 15 minutes and then exposing to a condition of 125° C. for 15 minutes was performed 500 cycles. The resistance value between the first conductor layer and the second conductor layer of the via-hole conductor before and after passing the test was measured, and the rate of change thereof was evaluated in the following manner. A: The rate of change in resistance value before and after the temperature cycle test was less than 8%. B: The change rate of the resistance value before and after the temperature cycle test is 8% or more and less than 10%. C: The change rate of the resistance value before and after the temperature cycle test is 10% or more.

The results of the evaluation tests described above are shown in Tables 4 to 6 below.

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

[Table 6]

1: Substrate 2: Insulation layer 3: Second conductor layer 4: film 5: Non-hardened part 6: Through hole 61: first end 62: second end 63: small diameter part 7: Interlayer insulating layer 8: The first conductor layer 9: Through hole conductor 11: Printed circuit board

Fig. 1 A, Fig. 1 B, Fig. 1 C, Fig. 1 D, and Fig. 1 E are cross-sectional views showing steps of manufacturing a printed wiring board.

Domestic deposit information (please note in order of depositor, date, and number) none Overseas storage information (please note in order of storage country, institution, date, and number) none

1: Substrate

2: Insulation layer

3: Second conductor layer

4: film

5: Non-hardened part

6: Through hole

61: first end

62: second end

63: small diameter part

7: Interlayer insulating layer

8: The first conductor layer

9: Through hole conductor

11: Printed circuit board

Claims (18)

A printed wiring board comprising: a first conductor layer; a second conductor layer; an interlayer insulating layer interposed between the first conductor layer and the second conductor layer; a through hole penetrating the interlayer insulating layer; and a through hole conductor arranged in the through hole and conducting the first conductor layer and the second conductor layer; The unsaturated compound (B) and the photopolymerization initiator (C), the said through hole has: a first end, which is the end on the side of the first conductor layer; a second end, which is the end on the side of the second conductor layer; and a small diameter part, which is located between the first end and the second end and has a diameter smaller than the diameter of the second end, and the minimum diameter of the small diameter part is more than 65% and less than 100% of the diameter of the second end. The printed wiring board according to claim 1, wherein the diameter of the first end is 65% or more of the diameter of the second end. The printed wiring board according to claim 1 or 2, wherein the diameter of the first end is 100 μm or less. The printed wiring board according to claim 1 or 2, wherein the carboxyl group-containing resin (A) contains a carboxyl group-containing resin having a bisphenol-skeleton skeleton. The printed wiring board as claimed in item 1 or 2, wherein, The weight average molecular weight of the said carboxyl group-containing resin (A) is 700-100000. The printed wiring board according to claim 1 or 2, wherein the carboxyl group-containing resin (A) contains a component having an acid value of 65 mgKOH/g or more and 150 mgKOH/g or less. The printed wiring board according to claim 1 or 2, wherein the percentage of the unsaturated compound (B) is 5% by mass or more and 45% by mass or less with respect to the carboxyl group-containing resin (A). The printed wiring board according to claim 1 or 2, wherein the percentage of the photopolymerization initiator (C) is 1% by mass or more and 30% by mass or less with respect to the carboxyl group-containing resin (A). The printed circuit board according to claim 1 or 2, wherein the photopolymerization initiator (C) contains at least one selected from the group consisting of an acylphosphine oxide-based photopolymerization initiator, an α-aminoalkylphenone-based photopolymerization initiator, and an oxime ester-based photopolymerization initiator. The printed wiring board according to claim 1 or 2, wherein the photosensitive resin composition further contains an epoxy resin (D). The printed wiring board according to claim 10, wherein the epoxy resin (D) has an equivalent of epoxy groups of 0.1 to 5 relative to 1 equivalent of carboxyl groups of the carboxyl group-containing resin (A). The printed wiring board according to claim 1 or 2, wherein the photosensitive resin composition further contains an organic filler (E). The printed wiring board according to claim 12, wherein the organic filler (E) has a reactive group. The printed wiring board according to claim 13, wherein the reactive group includes at least one group selected from the group consisting of carboxyl group, amine group, epoxy group, vinyl group and hydroxyl group. The printed wiring board according to claim 12, wherein the ratio of the organic filler (E) to the carboxyl group-containing resin (A) is 1% by mass or more and 100% by mass or less. A method for manufacturing a printed circuit board, which is a method for manufacturing the printed circuit board described in any one of Claims 1 to 15, and includes: preparing a negative-type aforementioned photosensitive resin composition and a substrate, the photosensitive resin composition containing: the aforementioned carboxyl group-containing resin (A), the aforementioned unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and the aforementioned photopolymerization initiator (C); the substrate has an insulating layer and the aforementioned second conductor layer stacked on the aforementioned insulating layer; The prepared film is superimposed on the substrate so as to cover the second conductor layer; after exposing the negative pattern-shaped region of the film including the pattern of the via hole, a development treatment is performed using an alkaline aqueous solution to form the interlayer insulating layer and the via hole penetrating the interlayer insulating layer. The method of manufacturing a printed wiring board according to claim 16, comprising: forming the coating film by superimposing a dry film made of the photosensitive resin composition on the substrate. The method for manufacturing a printed wiring board according to claim 16 or 17, wherein when exposing the coating film, the coating film is irradiated with specific light, the specific light being at least one of wavelength ranges of 365nm±65nm wavelengths have spectral intensity and wavelengths above 435nm have no spectral intensity.