CN114449745A

CN114449745A - Printed wiring board and method for manufacturing printed wiring board

Info

Publication number: CN114449745A
Application number: CN202111306408.8A
Authority: CN
Inventors: 樋口伦也; 藤原勇佐; 桥本壮一; 荒井贵
Original assignee: Goo Chemical Industries Co Ltd
Current assignee: Goo Chemical Industries Co Ltd
Priority date: 2020-11-06
Filing date: 2021-11-05
Publication date: 2022-05-06
Also published as: TW202225844A; TWI807464B

Abstract

The present disclosure provides a printed wiring board having a via with high conduction reliability. A printed wiring board (11) is provided with a first conductor layer (8), a second conductor layer (3), an interlayer insulating layer (7), a through hole (6) penetrating the interlayer insulating layer (7), and a via conductor (9) arranged in the through hole (6). 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) on the first conductor layer (8) side, a second end (62) on the second conductor layer (3) side, and a small diameter section (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

Technical Field

The present disclosure relates generally to a printed wiring board and a method for manufacturing a printed wiring board, and more particularly, to a printed wiring board including an interlayer insulating layer having a through hole and a via conductor, and a method for manufacturing the printed wiring board.

Background

In a printed wiring board, a via may be formed in an interlayer insulating layer.

For example, patent document 1 discloses a method for manufacturing a multilayer printed wiring board, including the steps of: a blind via having a top diameter of 100 [ mu ] m or less is formed by irradiating a plastic film, which is in close contact with the surface of an insulating layer containing 35 mass% or more of an inorganic filler, with a carbon dioxide laser.

Patent document 1: japanese patent laid-open publication No. 2016-181731

Disclosure of Invention

The disclosed subject matter provides a printed wiring board having a via with high conduction reliability and a method for manufacturing the printed wiring board.

A printed wiring board according to an aspect of the present disclosure 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 electrically connecting the first conductor layer and the second conductor layer. The interlayer insulating layer 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 has a first end, a second end, and a small diameter portion, the first end is an end on the side of the first conductor layer, the second end is an end on the side of the second conductor layer, and the small diameter portion 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 disclosure is a method for manufacturing the printed wiring board, including: preparing a negative photosensitive resin composition containing the carboxyl group-containing resin (a), the unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, and the photopolymerization initiator (C), and a substrate having an insulating layer and the second conductor layer overlapping the insulating layer; superposing a coating film made of the photosensitive resin composition on the substrate so as to cover the second conductor layer; the interlayer insulating layer and the through-hole penetrating the interlayer insulating layer are formed by exposing a negative pattern region of the film including the pattern of the through-hole to light and then performing a development treatment using an aqueous alkaline solution.

According to one embodiment of the present disclosure, a printed wiring board having a via with high conduction reliability and a method for manufacturing the printed wiring board can be provided.

Drawings

Fig. 1A is a sectional view showing a process of manufacturing a printed wiring board.

Fig. 1B is a sectional view showing a process of manufacturing a printed wiring board.

Fig. 1C is a sectional view showing a process of manufacturing a printed wiring board.

Fig. 1D is a sectional view showing a process of manufacturing a printed wiring board.

Fig. 1E is a sectional view showing a process of manufacturing a printed wiring board.

Description of the symbols

3 second conductor layer

4 coating film

6 through hole

61 first end

62 second end

63 minor diameter portion

7 interlayer insulating layer

8 first conductor layer

9-channel conductor

Detailed Description

(1) Detailed description of the subject

In japanese patent laid-open publication No. 2016-181731, a method of manufacturing a multilayer printed wiring board is disclosed, which comprises the steps of: a blind via having a top diameter of 100 [ mu ] m or less is formed by irradiating a plastic film, which is in close contact with the surface of an insulating layer containing 35 mass% or more of an inorganic filler, with a carbon dioxide laser. However, according to the findings of the inventors, the invention described in japanese patent application laid-open No. 2016-181731 has room for improvement in the conduction reliability of the path. The conduction reliability of the tapered via is likely to be lowered.

The inventors of the present invention have made investigations and developments on the material of the interlayer insulating layer, and have found that cracks may occur in the via conductor of the interlayer insulating layer, which degrades the conduction reliability.

Therefore, the inventors have conducted research and development to provide a printed wiring board having a via with high conduction reliability and a method for manufacturing the printed wiring board, and as a result, have completed the present disclosure.

(2) Summary of the invention

One embodiment of the present disclosure will be explained.

The printed wiring board 11 of the present embodiment includes a first conductor layer 8, a second conductor layer 3, an interlayer insulating layer 7 interposed between the first conductor layer 8 and the second conductor layer 3, a through hole 6 penetrating the interlayer insulating layer 7, and a via conductor 9 (see fig. 1E) disposed in the through hole 6 and electrically connecting the first conductor layer 8 and the second conductor layer 3. 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, a second end 62, and a small diameter portion 63, the first end 61 being the end on the first conductor layer 8 side, the second end 62 being the end on the second conductor layer 3 side, and the small diameter portion 63 being located between the first end 61 and the second end 62 and having a diameter smaller than that of the second end 62.

In the present embodiment, the interlayer insulating layer 7 is made 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). Therefore, the interlayer insulating layer 7 is produced by exposing the film 4 made of the photosensitive resin composition in a pattern and then developing it with an alkaline aqueous solution, and the through-hole 6 having the small diameter portion 63 is easily produced.

The reason why the small diameter portion 63 is easily formed is presumed as follows. When the surface of the film 4 formed of the negative photosensitive resin composition, on which the first end 61 of the through hole 6 is formed, is irradiated with light, the light is scattered inside the film 4 at the time of exposure of the film 4, and the wider portion is more easily cured as the depth of the film 4 is closer. This gradually reduces the uncured portion 5 that becomes the through-hole 6, and facilitates formation of the small diameter portion 63 having a smaller diameter than the first end 61. Further, on the deeper side within the film 4, light is absorbed by the film 4, and the light is hard to reach, and the influence of scattering of light is reduced, and therefore, the film 4 is hard to be cured, and therefore, the diameter of the second end 62 is larger than the diameter of the small diameter portion 63, and the through hole 6 is likely to have a shape widening from the small diameter portion 63 to the second end 62.

Particularly, the photosensitive resin composition preferably has the following properties: when a coating 4 having a film thickness of 5 μm to 100 μm is formed from a photosensitive resin composition, ultraviolet rays having a spectral intensity at least one wavelength in a wavelength region of 365nm + -65 nm are irradiated to a region of the coating 4 other than a circular portion having a diameter of 5 μm to 100 μm, and then the coating 4 is subjected to a developing treatment with an alkaline aqueous solution, a through-hole 6 is formed in the circular portion, and the through-hole 6 has a small diameter portion 63. In this case, the diameter of the small diameter portion 63 of the through hole 6 is preferably 65% or more and less than 100% of the diameter of the second end 62, the diameter of the first end 61 is preferably 65% or more of the diameter of the second end 62, and the diameter of the first end 61 is preferably 100 μm or less. Such characteristics can be achieved within the range of the composition of the photosensitive resin composition described in detail later. The method of irradiating the film 4 with ultraviolet light may be an exposure method using a negative mask or a direct drawing method. Examples of specific test methods and conditions are set forth in the examples section.

In the present embodiment, the through-hole 6 has such a shape that even when stress is generated in the via conductor 9 by applying a load or the like due to heat to the via conductor 9, cracks are less likely to be generated at the interface between the via conductor 9 and the second conductor layer 3. Therefore, good conduction reliability between the first conductor layer 8 and the second conductor layer 3 is easily obtained by the via. This is presumably because, in the present embodiment, as described above, the inner surface of the through 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, and therefore, even if stress is generated in the via conductor 9, stress is more likely to concentrate on the small diameter portion 63 than on the second end 62 of the via.

The minimum diameter of the small-diameter portion 63 is preferably 65% or more and less than 100% of the diameter of the second end 62. In this case, the conduction reliability by the via is particularly easily obtained. The minimum diameter of the small diameter portion 63 is preferably 95% or less of the diameter of the second end 62, and more preferably 90% or less. The minimum diameter of the small diameter portion 63 is preferably 67% or more, more preferably 79% or more, of the diameter of the second end 62.

The diameter of the first end 61 is preferably 65% or more relative to the diameter of the second end 62. At this time, the via conductor 9 can be easily produced by immersing the plating solution into the through-hole 6. That is, the via conductor 9 can be easily formed by the plating method. Therefore, further excellent conduction reliability is easily obtained. From the viewpoint of obtaining a good resolution in manufacturing the through hole 6, the diameter of the first end 61 is more preferably 70% or more, still more preferably 75% or more, and particularly preferably 80% or more, with respect to the diameter of the second end 62. In addition, the diameter of the first end 61 is preferably less than 130%, more preferably less than 120%, further preferably less than 110%, and particularly preferably less than 100% with respect to the diameter of the second end 62.

The diameter of the first end 61 is preferably 100 μm or less. At this time, the via conductor 9 can be easily formed in the through hole 6 by plating or the like. Therefore, further excellent conduction reliability is easily obtained. The diameter of the first end 61 is, for example, 5 μm or more.

(3) Photosensitive resin composition

The photosensitive resin composition of the present embodiment will be specifically described below in detail. In the following description, "(meth) acrylic acid" means at least one of "acrylic acid" and "methacrylic acid". For example, (meth) acrylate refers to 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) having a bisphenol fluorene skeleton represented by the following formula (1). When the carboxyl group-containing resin (a) has a bulky bisphenol fluorene skeleton, light is less likely to scatter at a deep portion when the film 4 made of the photosensitive resin composition is irradiated with ultraviolet light. Further, the carboxyl group-containing resin (a1) has a bisphenol fluorene skeleton, and thus can impart high heat resistance and insulation reliability to a cured product of the photosensitive resin composition.

In the formula (1), R₁～R₈Each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or a halogen. Namely, R in the formula (1)₁～R₈Each of which may be hydrogen, but may also be an alkyl group having 1 to 5 carbon atoms or a halogen. This is because, even if hydrogen in the aromatic ring is substituted with a low molecular weight alkyl group or a halogen, the physical properties of the carboxyl group-containing resin (a1) are not adversely affected, and instead, the heat resistance and flame retardancy of a cured product of the photosensitive resin composition containing the carboxyl group-containing resin (a1) may be improved.

The carboxyl group-containing resin (a1) is synthesized, for example, by reacting an epoxy compound (a1) having a bisphenol fluorene skeleton represented by formula (1) with an unsaturated group-containing carboxylic acid (a2), and reacting the intermediate thus obtained with an acid anhydride (a 3).

The epoxy compound (a1) has, for example, a structure represented by the following formula (2). N in the formula (2) is, for example, an integer in the range of 0 to 20. In order to appropriately control the molecular weight of the carboxyl group-containing resin (a1), the average value of n is more preferably in the range of 0 to 1. When the average value of n is in the range of 0 to 1, an excessive increase in the molecular weight of the carboxyl group-containing resin (A1) is easily suppressed. In the formula (2), R₁～R₈Each independently hydrogen, an alkyl group having 1 to 5 carbon atoms, or a halogen.

The unsaturated group-containing carboxylic acid (a2) contains, 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, a monomer selected from the group consisting of acrylic acid, methacrylic acid, ω -carboxy-polycaprolactone (n ≈ 2) monoacrylate, crotonic acid, cinnamic acid, 2-acryloyloxyethylsuccinic acid, 2-methacryloyloxyethylsuccinic acid, 2-acryloyloxyethylphthalic acid, 2-methacryloyloxyethylphthalic acid, 2-acryloyloxypropylphthalic acid, 2-acryloyloxyethylsuccinic acid, 2-methacryloyloxyethylmaleic acid, β -carboxyethyl acrylate, 2-acryloyloxyethyltetrahydrophthalic acid, 2-methacryloyloxyethyltetrahydrophthalic acid, 2-acryloyloxyethylhexahydrophthalic acid, and 2-methacryloyloxyethylhexahydrophthalic acid At least one compound of a dicarboxylic acid. Preferably, the unsaturated group-containing carboxylic acid (a2) contains acrylic acid. When the unsaturated group-containing carboxylic acid (a2) contains acrylic acid, the acrylic acid is contained in an amount of preferably 50 mol% or more, more preferably 80 mol% or more, still more preferably 85 mol% or more, and particularly preferably 90 mol% or more of the unsaturated group-containing carboxylic acid (a 2).

When the epoxy compound (a1) is reacted with the unsaturated group-containing carboxylic acid (a2), an appropriate method can be employed. For example, an unsaturated group-containing carboxylic acid (a2) is added to a solvent solution of an epoxy compound (a1), and further a thermal polymerization inhibitor and a catalyst are added as necessary and mixed with stirring, thereby obtaining a reactive solution. The intermediate can be obtained by reacting the reactive solution at a temperature of preferably 60 to 150 c, more preferably 80 to 120 c, by a conventional method. The solvent in this case may contain at least one component selected from ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, acetates such as ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate and propylene glycol monomethyl ether acetate, and dialkyl glycol ethers. The thermal polymerization inhibitor may contain, for example, at least one member selected from the group consisting of hydroquinone, methylhydroquinone, and hydroquinone monomethyl ether. The catalyst may contain at least one component selected from tertiary amines such as benzildimethylamine and triethylamine, quaternary ammonium salts such as trimethylbenzylammonium chloride and methyltriethylammonium chloride, triphenylphosphine and triphenylantimony.

The catalyst particularly preferably contains triphenylphosphine. That is, the epoxy compound (a1) is preferably reacted with the unsaturated group-containing carboxylic acid (a2) in the presence of triphenylphosphine. In this case, the ring-opening addition reaction of the epoxy group of the epoxy compound (a1) and the unsaturated group-containing carboxylic acid (a2) is particularly accelerated, and a reaction rate (conversion rate) of 95% or more, or 97% or more, or substantially 100% can be achieved.

It is also preferable to react the epoxy compound (a1) with the unsaturated group-containing carboxylic acid (a2) under bubbling of air. 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 gelation of the solution of the intermediate can be suppressed. In addition, excessive coloring of the carboxyl group-containing resin (a1) as a final product can be suppressed.

The unsaturated group-containing carboxylic acid (a2) in the reaction of the epoxy compound (a1) and the unsaturated group-containing carboxylic acid (a2) is preferably in an amount of 0.8 to 1.2 mol based on1 mol of the epoxy group of the epoxy compound (a 1). In this case, a photosensitive resin composition having excellent photosensitivity and stability can be obtained.

The intermediate thus obtained has a hydroxyl group formed in the reaction between the epoxy group of the epoxy compound (a1) and the carboxyl group of the unsaturated group-containing carboxylic acid (a 2).

Next, the intermediate is reacted with an acid anhydride (a 3). The acid anhydride (a3) contains, for example, acid dianhydride (a 4).

The acid dianhydride (a4) is a compound having 2 anhydride groups. The acid dianhydride (a4) may contain an anhydride of a tetracarboxylic acid. The acid dianhydride (a4) may contain, for example, a dianhydride selected from 1,2,4, 5-benzenetetracarboxylic acid dianhydride, benzophenone tetracarboxylic acid dianhydride, methylcyclohexene tetracarboxylic acid dianhydride, naphthalene-1, 4,5, 8-tetracarboxylic acid dianhydride, ethylene tetracarboxylic acid dianhydride, 9 '-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, glycerol bis (trimellitate ester) monoacetate, ethylene glycol bis trimellitate ester, 3, 3', 4,4 '-diphenylsulfone tetracarboxylic acid dianhydride, 1,3,3a,4,5,9 b-hexahydro-5 (tetrahydro-2, 5-dioxo-3-furanyl) naphtho [ 1,2-c ] furan-1, 3-dione, 1,2,3, 4-butanetetracarboxylic acid dianhydride and 3, 3', at least one compound selected from 4, 4' -biphenyltetracarboxylic dianhydride. Particularly preferably, the acid dianhydride (a4) contains 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride. In this case, the adhesiveness of the coating 4 made of the photosensitive resin composition can be suppressed while ensuring good developability of the photosensitive resin composition, and the insulation reliability and plating resistance of the cured product can be improved.

The acid anhydride (a3) may contain an acid monoanhydride (a 5). The acid monoanhydride (a5) is a compound having one acid anhydride group. The acid monoanhydride (a5) may comprise an anhydride of a dicarboxylic acid. The acid monoanhydride (a5) may contain, for example, at least one compound selected from 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-tricarboxylic acid-1, 2-anhydride, and itaconic anhydride. It is particularly preferred that the acid monoanhydride (a5) contains 1,2,3, 6-tetrahydrophthalic anhydride. That is, the acid anhydride (a3) preferably contains 1,2,3, 6-tetrahydrophthalic anhydride. In this case, the adhesiveness of the coating 4 formed of the photosensitive resin composition can be further suppressed while ensuring good developability of the photosensitive resin composition, and the insulation reliability and plating resistance of the cured product can be further improved. The 1,2,3, 6-tetrahydrophthalic anhydride is preferably in the range of 20 to 100 mol%, more preferably 40 to 100 mol%, based on the whole amount of the acid monoanhydride (a5), but the present invention is not limited thereto.

When the intermediate is reacted with the acid anhydride (a3), an appropriate method can be employed. For example, the acid anhydride (a3) is added to a solvent solution of the intermediate, and if necessary, a thermal polymerization inhibitor and a catalyst are further added and mixed with stirring, thereby obtaining a reactive solution. The reactive solution is reacted at a temperature of preferably 60 to 150 ℃, particularly preferably 80 to 120 ℃ by a conventional method, thereby obtaining a carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton. As the solvent, catalyst and polymerization inhibitor, any suitable one may be used, and the solvent, catalyst and polymerization inhibitor used in the synthesis of the intermediate may be used as it is.

The catalyst particularly preferably contains triphenylphosphine. That is, the intermediate is reacted with the acid anhydride (a3), preferably in the presence of triphenylphosphine. In this case, the reaction between the intermediate and the acid anhydride (a3) is particularly promoted, and a reaction rate (conversion rate) of 90% or more, 95% or more, 97% or more, or substantially 100% can be achieved.

When the acid anhydride (a3) contains the acid dianhydride (a4), the amount of the acid dianhydride (a4) is preferably 0.05 to 0.24 mol based on1 mol of the epoxy group of the epoxy compound (a 1). In this case, the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton, the acid value and molecular weight of which are appropriately adjusted, can be easily obtained.

When the acid anhydride (a3) further contains the acid monoanhydride (a5), the amount of the acid monoanhydride (a5) is preferably 0.3 to 0.7 mol based on1 mol of the epoxy group in the epoxy compound (a 1). In this case, the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton, the acid value and molecular weight of which are appropriately adjusted, can be easily obtained.

It is also preferred to react the intermediate with the acid anhydride (a3) under air sparging. In this case, excessive increase in the molecular weight of the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton produced can be suppressed, and thus the developability of the photosensitive resin composition with an alkaline aqueous solution is particularly improved.

The components other than the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton in the photosensitive resin composition will be described.

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

The carboxyl group-containing resin (a) may contain only the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton, or may contain only a carboxyl group-containing resin other than the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton. Alternatively, both of the carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton and the carboxyl group-containing resin other than the carboxyl group-containing resin (a1) may be contained. The carboxyl group-containing resin other than the carboxyl group-containing resin having a bisphenol fluorene skeleton (a1) includes a carboxyl group-containing resin not having a bisphenol fluorene skeleton (hereinafter also referred to as a carboxyl group-containing resin (a 2)).

The carboxyl group-containing resin (a2) may contain, for example, a compound having a carboxyl group and not having photopolymerization (hereinafter referred to as component (a 2-1)). The component (A2-1) contains, for example, a polymer of an ethylenically unsaturated monomer containing an ethylenically unsaturated compound having a carboxyl group. The ethylenically unsaturated compound having a carboxyl group may contain compounds such as acrylic acid, methacrylic acid, and ω -carboxy-polycaprolactone (n ≈ 2) monoacrylate. The ethylenically unsaturated compound having a carboxyl group may also contain a reaction product of pentaerythritol triacrylate, pentaerythritol trimethacrylate, or the like with a dibasic acid anhydride. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound having no carboxyl group, such as 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate, or a (meth) acrylate having a linear or branched aliphatic or alicyclic group (wherein the ring may have a part of an unsaturated bond).

The carboxyl group-containing resin (a2) may contain a compound having a carboxyl group and an ethylenically unsaturated group (hereinafter referred to as component (a 2-2)). The carboxyl group-containing resin (A2) may contain only the component (A2-2). The component (a2-2) contains, for example, a resin (referred to as a first resin (x)) which is a reactant of an epoxy compound (x1) having two or more epoxy groups in one molecule and an ethylenically unsaturated compound (x2) and at least one compound (x3) selected from a polycarboxylic acid and an anhydride thereof as an intermediate. The first resin (x) is obtained, for example, by adding the compound (x3) to an intermediate obtained by reacting an epoxy group in the epoxy compound (x1) with a carboxyl group in the ethylenically unsaturated compound (x 2). The epoxy compound (x1) may contain an appropriate epoxy compound such as a cresol novolak type epoxy compound, a phenol novolak type epoxy compound, a biphenol novolak type epoxy compound, and the like. It is particularly preferable that the epoxy compound (x1) contains at least 1 compound selected from the group consisting of diphenol novolak type epoxy compounds and cresol novolak type epoxy compounds. The epoxy compound (x1) may contain only a diphenol 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 of corrosion of the cured product of the photosensitive resin composition by an oxidizing agent containing potassium permanganate, for example, can be significantly 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, and further contains a compound (z2) having no epoxy group such as 2- (meth) acryloyloxyethyl phthalate. The ethylenically unsaturated compound (x2) preferably contains at least one of acrylic acid and methacrylic acid. The compound (x3) contains, for example, at least one compound selected from polycarboxylic acids such as phthalic acid, tetrahydrophthalic acid, and methyltetrahydrophthalic acid, and anhydrides of these polycarboxylic acids. It is particularly preferred that the compound (x3) contains at least 1 polycarboxylic acid selected from phthalic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid.

The component (a2-2) may contain a resin (referred to as a second resin (y)) which is a reactant 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 having no carboxyl group. The second resin (y) is obtained by reacting an ethylenically unsaturated compound having an epoxy group with a part of the carboxyl groups in the polymer. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound having no carboxyl group. The ethylenically unsaturated compound having a carboxyl group contains compounds such as acrylic acid, methacrylic acid, ω -carboxy-polycaprolactone (n ≈ 2) monoacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, and the like. The ethylenically unsaturated compound having no carboxyl group includes compounds such as 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate, and (meth) acrylic esters of linear or branched aliphatic or alicyclic groups (wherein, a part of unsaturated bonds may be present in the ring). The ethylenically unsaturated compound having an epoxy group preferably contains glycidyl (meth) acrylate.

The carboxyl group-containing resin (a) contains only the carboxyl group-containing resin (a1), only the carboxyl group-containing resin (a2), or both the carboxyl group-containing resin (a1) and the carboxyl group-containing resin (a 2). The carboxyl group-containing resin (a) preferably contains 25% by mass or more of the carboxyl group-containing resin (a1), more preferably 40% by mass or more, still more preferably 60% by mass or more, and particularly preferably 100% by mass. In this case, excellent photosensitivity of the photosensitive resin composition and developability with an alkaline aqueous solution can be ensured. In addition, the heat resistance and insulation reliability of a cured product of the photosensitive resin composition can be particularly improved. Further, the viscosity 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 to 100000. If the weight average molecular weight of the carboxyl group-containing resin (a) is 700 or more, the viscosity of the coating film 4 formed from the photosensitive resin composition can be easily suppressed, 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 100000 or less, the developability of the photosensitive resin composition with an alkaline aqueous solution is easily improved. The weight average molecular weight of the carboxyl group-containing resin (A) is more preferably 900 to 60000, still more preferably 1200 to 10000, and particularly preferably 1400 to 5000. The weight average molecular weight of the carboxyl group-containing resin (a) can be calculated from the measurement results by gel permeation chromatography under the following conditions, for example.

GPC apparatus: shodex System 11 manufactured by Shorey electrician,

column: SHODEX KF-800P, KF-005, KF-003 and KF-0014 are connected in series,

mobile phase: the reaction mixture of THF and water is treated by the following steps of THF,

flow rate: 1 ml/min of the mixture is added,

column temperature: at a temperature of 45 c,

a detector: the amount of the RI,

conversion: polystyrene.

The carboxyl group-containing resin (A) preferably contains a component having an acid value of 65mgKOH/g to 150 mgKOH/g. In this case, the developability of the photosensitive resin composition with an alkaline aqueous solution is particularly improved, and the through-hole 6 having the small diameter portion 63 is particularly easily produced by developing the exposed coating 4 with an alkaline aqueous solution. The acid value is more preferably from 70mgKOH/g to 145mgKOH/g, still more preferably from 75mgKOH/g to 140mgKOH/g, and particularly preferably from 85mgKOH/g to 135 mgKOH/g.

The unsaturated compound (B) can impart photocurability to the photosensitive resin composition. The unsaturated compound (B) may contain, for example, a monofunctional (meth) acrylate selected from 2-hydroxyethyl (meth) acrylate and the like; and at least one compound selected from polyfunctional (meth) acrylates such as diethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epsilon-caprolactone-modified pentaerythritol hexaacrylate, and tricyclodecane dimethanol di (meth) acrylate.

Particularly preferably, the unsaturated compound (B) contains a trifunctional compound, i.e., a compound having 3 unsaturated bonds in one molecule. In this case, the resolution of the film 4 formed of the photosensitive resin composition at the time of exposure and development is improved, and the developability of the photosensitive resin composition with an alkaline aqueous solution is particularly improved. The trifunctional compound may contain, for example, at least one compound selected from trimethylolpropane tri (meth) acrylate, EO-modified trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, ethoxylated isocyanuric acid tri (meth) acrylate and ε -caprolactone-modified tris- (2-acryloyloxyethyl) isocyanurate and ethoxylated glycerin tri (meth) acrylate.

The unsaturated compound (B) also preferably 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 may contain, for example, a compound selected from the group consisting of 2-methacryloyloxyethyl acid phosphate (product numbers LIGHT ESTER P-1M and LIGHT ESTER P-2M manufactured by Kyoeisha chemical Co., Ltd.), 2-acryloyloxyethyl acid phosphate (product number LIGHT ACRYLATE P-1A manufactured by Kyoeisha chemical Co., Ltd., example), diphenyl-2-methacryloyloxyethyl phosphate (product number MR-260 manufactured by Daba Industrial Co., Ltd., example), and HFA series (product numbers HFA-6003 and HFA-6007 which are addition reaction products of dipentaerythritol hexaacrylate and HCA (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) manufactured by Showa high molecular Co., Ltd., at least one compound of product numbers HFA-3003 and HFA-6127, etc.) as an addition reaction product of caprolactone-modified dipentaerythritol hexaacrylate and HCA (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide).

The unsaturated compound (B) may contain a prepolymer. The prepolymer may 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 then adding an ethylenically unsaturated group, and an oligomeric (meth) acrylate prepolymer. The oligo (meth) acrylate prepolymer may contain at least one component selected from the group consisting of epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) acrylate, alkyd (meth) acrylate, silicone (meth) acrylate, and spiro-alkane resin (meth) acrylate, for example.

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. In this case, when the photosensitive resin composition is exposed to ultraviolet light, high light absorption can be imparted to the photosensitive resin composition. If the photosensitive resin composition has good light absorption, light is easily absorbed when the film 4 formed of the photosensitive resin composition is exposed, and therefore, photocuring is easily performed. Further, the light is absorbed in the film 4, so that the amount of light reaching the deep part is reduced. Therefore, the influence of scattering of light is less likely to occur particularly in the deep portion, and the film 4 is less likely to be photocured particularly in the deep portion than in the surface. Therefore, when the through hole 6 is formed by photolithography, the small diameter portion 63 is particularly easily formed.

The photopolymerization initiator (C1) more preferably contains an acylphosphine oxide photopolymerization initiator. In this case, the photosensitive resin composition can be provided with higher light absorption.

The acylphosphine oxide-based photopolymerization initiator may contain, for example, a monoacylphosphine oxide-based photopolymerization initiator selected from 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4, 6-trimethylbenzoyl-ethyl-phenyl-phosphinic acid ester and the like, 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, at least one component selected from bisacylphosphine oxide photopolymerization initiators such as 4, 4-trimethylpentylphosphine oxide, bis- (2, 6-dimethoxybenzoyl) -2, 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 preferably contains at least one of 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide and bis- (2,4, 6-trimethylbenzoyl) phenylphosphine oxide, and more preferably contains 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide.

The α -aminoalkylphenone-based photopolymerization initiator may contain at least one component selected from, for example, 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one and 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone.

The oxime ester photopolymerization initiator may contain at least one component selected from 1, 2-octanedione-1- [4- (phenylthio) -2- (oxo-benzoyloxime) ], and ethanone-1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] -1- (O-acetyloxime).

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

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

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

It is also preferable that the photopolymerization initiator (C) contains 4, 4-bis (diethylamino) benzophenone (C3). That is, it is also preferable that the photosensitive resin composition contains a photopolymerization initiator (C1) and 4, 4-bis (diethylamino) benzophenone (C3), or contains a photopolymerization initiator (C1), a photopolymerization initiator (C2) and 4, 4-bis (diethylamino) benzophenone (C3). In this case, when the film 4 formed of the photosensitive resin composition is developed after being partially exposed to light, it is particularly easy to suppress the curing of the unexposed portion. Therefore, the through-hole 6 having the small diameter portion 63 is particularly easily formed.

The 4, 4-bis (diethylamino) benzophenone (C3) is preferably contained in an amount of 0.5 to 20% by mass based on the photopolymerization initiator (C1). When the amount of 4, 4-bis (diethylamino) benzophenone (C3) is 0.5% by mass or more, the curing of the unexposed portion is particularly easily inhibited. In addition, if the 4, 4-bis (diethylamino) benzophenone (C3) is 20% by mass or less, the electrical insulation of the cured product of the photosensitive resin composition is not easily impaired by the 4, 4-bis (diethylamino) benzophenone (C3). The bis (diethylamino) benzophenone (C3) is particularly preferably in the range of 1 to 18% by mass relative to the photopolymerization initiator (C1). When the photosensitive resin composition contains the organic filler (E), the organic filler (E) may cause light scattering in the photosensitive resin composition during exposure. In this case, there is a possibility that a problem that a good resolution cannot be obtained by the photosensitive resin composition arises. 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 in the above range, the photosensitive resin composition tends to have a good resolution, and thus the small diameter portion 63 is particularly likely to be formed 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. The epoxy resin (D) may further contain an amorphous epoxy resin. Here, the "crystalline epoxy resin" is an epoxy resin having a melting point, and the "amorphous epoxy resin" is an epoxy resin having no melting point.

The crystalline epoxy resin preferably contains, for example, a compound selected from the group consisting of 1,3, 5-tris (2, 3-epoxypropyl) -1,3, 5-triazine-2, 4,6(1H,3H,5H) -trione, a hydroquinone-type crystalline epoxy resin (trade name YDC-1312, manufactured by Nissan chemical & materials Co., Ltd., as a specific example), a biphenyl-type crystalline epoxy resin (trade name YX-4000, manufactured by Mitsubishi chemical Co., Ltd., as a specific example), a diphenyl ether-type crystalline epoxy resin (product number YSLV-80DE, manufactured by Nissan chemical & materials Co., Ltd., as a specific example), a bisphenol-type crystalline epoxy resin (trade names YSLV-70XY and YSLV-80XY, manufactured by Nissan chemical & materials Co., Ltd., as a specific example), and a tetraphenolene-type crystalline epoxy resin (product number GTR-1800, manufactured by Nissan chemical Co., Ltd., as a specific example), Bisphenol fluorene type crystalline epoxy resin.

The crystalline epoxy resin preferably has 2 or more epoxy groups in 1 molecule. In this case, the cured product of the photosensitive resin composition can be made less likely to crack during repeated temperature changes.

The crystalline epoxy resin preferably has an epoxy equivalent of 150 to 300 g/eq. The epoxy equivalent is a gram weight of a crystalline epoxy resin containing 1 gram equivalent of an epoxy group. The crystalline epoxy resin has a melting point. The melting point of the crystalline epoxy resin is, for example, 70 to 180 ℃.

It is particularly preferable that the epoxy compound (D) contains a crystalline epoxy resin having a melting point of 110 ℃ or lower. In this case, the developability of the photosensitive resin composition with an alkaline aqueous solution is particularly improved. The crystalline epoxy resin having a melting point of 110 ℃ or lower may contain at least one component selected from, for example, biphenyl type epoxy resins (product No. YX-4000 manufactured by Mitsubishi chemical Co., Ltd., as a specific example), diphenyl ether type epoxy resins (product No. YSLV-80DE manufactured by Nikko chemical & materials chemical Co., Ltd., as a specific example), bisphenol type epoxy resins (product Nos. YSLV-70XY and YSLV-80XY manufactured by Nikko chemical & materials Co., Ltd., as a specific example), and bisphenol fluorene type crystalline epoxy resins.

The amorphous epoxy resin is preferably selected from the group consisting of phenol novolac type epoxy resin (product number EPICLON-775 manufactured by DIC corporation, as a specific example), cresol novolac type epoxy resin (product number EPICLON-695 manufactured by DIC corporation, as a specific example), bisphenol A novolac type epoxy resin (product number EPICLON-865 manufactured by DIC corporation, as a specific example), bisphenol A type epoxy resin (product number jER1001 manufactured by Mitsubishi chemical corporation, as a specific example), bisphenol F type epoxy resin (product number jER4 4004P manufactured by Mitsubishi chemical corporation, as a specific example), bisphenol S type epoxy resin (product number EPICLON EXA-1514 manufactured by DIC corporation, as a specific example), bisphenol AD type epoxy resin, and biphenol novolac type epoxy resin (product number NC-3000 manufactured by Nihon chemical corporation, as a specific example), Hydrogenated bisphenol A type epoxy resin (as a specific example, product No. ST-4000D manufactured by Nippon chemical & materials Co., Ltd.), naphthalene type epoxy resin (as a specific example, product No. EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770 manufactured by DIC Co., Ltd.), tert-butyl catechol type epoxy resin (as a specific example, product No. EPICLON HP-820 manufactured by DIC Co., Ltd.), dicyclopentadiene type epoxy resin (as a specific example, product No. EPICLON HP-7200 manufactured by DIC), adamantane type epoxy resin (as a specific example, product No. ADANANTATEX-E-201 manufactured by shinning Kabushiki Kaisha), and special bifunctional type epoxy resins (as specific examples, product Nos. YL7175-500 and YL7175-1000 manufactured by Mitsubishi chemical Co., Ltd.; product No. EPICLON R-960, EPICLON TER-601, EPILON TSR-250-80BX, EPICLON1650-75MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822, and EPICLON EXA-9726; at least one component selected from the group consisting of a rubber-like core-shell polymer-modified bisphenol A type epoxy resin (product No. MX-156 made by Bell chemical Co., Ltd., as a specific example), a rubber-like core-shell polymer-modified bisphenol F type epoxy resin (product No. MX-136 made by Bell chemical Co., Ltd., as a specific example), and a rubber particle-containing bisphenol F type epoxy resin (product No. Kaneace MX-130 made by Bell chemical Co., Ltd., as a specific example).

When the photosensitive resin composition contains the epoxy resin (D), the photosensitive resin composition preferably contains both a crystalline epoxy resin and a non-crystalline epoxy resin. In this case, the plating resistance and the insulation property of the cured product made of 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 be contained in an amorphous epoxy resin. Examples of the phosphorus-containing epoxy resin include phosphoric acid-modified bisphenol F type epoxy resins (product numbers EPICLON EXA-9726 and EPICLON EXA-9710 available from DIC corporation), and EPOTHOO FX-305 available from Nippon chemical & materials corporation.

The photosensitive resin composition preferably does not contain a filler. At this time, the through-hole 6 having the small diameter portion 63 is particularly easily formed by suppressing scattering of light at the deep portion of the coating 4. When the photosensitive resin composition contains a filler, the material, particle size, and blending amount of the filler are preferably appropriately set so that scattering of light is not easily generated in the film 4.

The photosensitive resin composition may contain an organic filler (E). The organic filler (E) does not contain melamine. In this case, the material, particle size and blending amount of the organic filler (E) are preferably appropriately set as described above. The organic filler (E) imparts thixotropy to the photosensitive resin composition, thereby improving the storage stability of the photosensitive resin composition. In addition, the adhesion between the cured product and the plating layer is improved. The organic filler (E) preferably has a reactive group. The organic filler (E) has a reactive group, and thus has high compatibility with the photosensitive resin composition, and imparts stronger thixotropy to the photosensitive resin composition, thereby further improving 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 group of the organic filler (E) more preferably contains at least one group selected from a carboxyl group, an amino group, an epoxy group, a vinyl group and a hydroxyl group, and further preferably contains at least one of a carboxyl group and an amino group. 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 of the organic filler (E) particularly preferably contains a carboxyl group. In this case, the developability of the photosensitive resin composition is improved. Meanwhile, the carboxyl group of the organic filler (E) can react with the epoxy resin (D) in the photosensitive resin composition upon thermal curing. Thus, the cured product after thermosetting can contain the organic filler (E) uniformly dispersed therein. Further, unreacted carboxyl groups of the organic filler (E) may be modified at the stage of roughening the surface of the cured product. That is, among the organic fillers (E) contained in the cured product, the organic filler (E) located in the vicinity of the surface of the cured product is easily modified at the stage of roughening the surface of the cured product. The organic filler (E) thus modified can be easily removed from the cured product when a rough surface is provided to the cured product. This can impart a rough surface to the surface of the cured product and improve the adhesion between the cured product and the plating layer. In addition, the organic filler (E) may contain a carboxyl group, whereby the unevenness of the coating film due to the fluidity of the photosensitive resin composition can be reduced. This makes it easy to make the thickness of the layer formed of the photosensitive resin composition uniform. In addition, the via hole 6 having the small diameter portion 63 is easily formed in the interlayer insulating layer 7 made of the photosensitive resin composition.

When the organic filler (E) contains a carboxyl group, the carboxyl group can be formed as a side chain in the product by polymerizing or crosslinking a carboxylic acid monomer 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. The organic filler (E) can improve the stability (particularly, storage stability) of the photosensitive resin composition because it improves the thixotropy of the photosensitive resin composition. Further, if 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, and the acid value of the organic filler (E) is preferably from 1mgKOH/g to 60mgKOH/g in terms of the acid value based on acid-base titration. If the acid value is less than 1mgKOH/g, the stability of the photosensitive resin composition and the developability of the cured product may be lowered. If the acid value is more than 60mgKOH/g, the reliability of moisture resistance of the cured product may be lowered. The acid value of the organic filler (E) is more preferably 3mgKOH/g to 40 mgKOH/g.

The average primary particle diameter of the organic filler (E) is preferably 1 μm or less. When the average primary particle diameter of the organic filler (E) is 1 μm or less, the photosensitive resin composition can be favorably developed. Further, the roughness of the rough surface formed on the cured product can be made small, the anchor effect becomes large as the surface area of the cured product increases, and the adhesion between the rough surface and the plating layer can be improved.

The lower limit of the average primary particle diameter of the organic filler (E) is not particularly limited, and is preferably 0.001 μm or more, for example. Average primary particle diameter was measured by a laser diffraction particle size distribution measuring apparatus using D₅₀Is measured. The average primary particle diameter of the organic filler (E1) is more preferably 0.4 μm or less, and still more preferably 0.1 μm or less. In this case, scattering of light in the photosensitive resin composition during exposure can be suppressed, and thus the resolution of the photosensitive resin composition is further improved, and the through-hole 6 having the small diameter portion 63 can be easily formed in the interlayer insulating layer 7. In addition, the roughness of the rough surface formed on the cured product can be particularly fine.

The organic filler (E) is preferably dispersed in the photosensitive resin composition at a maximum particle diameter of less than 1.0. mu.m, more preferably less than 0.5. mu.m. The maximum particle diameter is determined by a laser diffraction particle size distribution measuring apparatus using D₅₀Is determined by the form of (1). Alternatively, the maximum particle size is measured by observing the cured product with a Transmission Electron Microscope (TEM). The organic filler (E) may be aggregated in the photosensitive resin composition (for example, secondary particles may be formed), and in this case, the maximum particle diameter refers to the size of the aggregated particles. If the maximum particle diameter of the organic filler (E) in the dispersed state is in the above-mentioned range, exposure is conductedScattering of light is suppressed in the photosensitive resin composition, and thus the resolution of the photosensitive resin composition is further improved, and the through-hole 6 having the small diameter portion 63 is more easily formed in the interlayer insulating layer 7. Further, the roughness of the rough surface formed on the cured product can be further reduced. When the particles are aggregated, the maximum particle diameter is generally larger than the average primary particle diameter.

The organic filler (E) preferably contains a rubber component. In addition, the organic filler (E) preferably contains only a rubber component. The rubber component can impart flexibility to a cured product of the photosensitive resin composition. The rubber component may be composed of a resin. The rubber component preferably contains at least one polymer selected from the group consisting of crosslinked acrylic rubber, crosslinked NBR, crosslinked MBS and crosslinked SBR. In this case, the rubber component can impart excellent flexibility to the cured product of the photosensitive resin composition. Further, a more appropriate rough surface can be provided to the surface of the cured product. Here, the rubber component contains a crosslinked structure formed when monomers constituting the polymer are copolymerized. NBR is generally a copolymer of butadiene and acrylonitrile, classified as nitrile rubber. MBS is generally a copolymer composed of 3 components of methyl methacrylate, butadiene, and styrene, and is classified as a butadiene rubber. SBR is generally a copolymer of styrene and butadiene, and is classified as a styrene rubber. Specific examples of the organic filler (E) include XER-91-MEK, a product number XER-32-MEK, and an XSK-500, which are product numbers of JSR Corp. XER-91-MEK is a crosslinked rubber (NBR) having a carboxyl group and an average primary particle diameter of 0.07. mu.m, and is provided as a methyl ethyl ketone dispersion containing 15% by weight of the crosslinked rubber, and has an acid value of 10.0 mgKOH/g. The XER-32-MEK is a dispersion in which a polymer (linear particles) of a carboxyl-modified hydrogenated nitrile rubber was dispersed in methyl ethyl ketone so that the content of the polymer was 17% by weight based on the total amount of the dispersion. In addition, XSK-500 is a crosslinked rubber (SBR) having a carboxyl group and a hydroxyl group and having an average primary particle diameter of 0.07. mu.m, provided as a dispersion of methyl ethyl ketone having a content ratio of 15% by weight of the crosslinked rubber. In this way, the organic filler (E) can be incorporated in the photosensitive resin composition in the form of a dispersion. That is, the rubber component may be blended in the photosensitive resin composition in the form of a dispersion. Specific examples of the organic filler (E) include, in addition to the above, product No. XER-92 manufactured by JSR Corp.

The photosensitive resin composition may contain a silane coupling agent. In this case, the dispersibility of the organic filler (E) can be improved. The resolution of the photosensitive resin composition can be further improved.

The silane coupling agent is, for example, a silane coupling agent containing a silicon atom and containing a compound selected from the group consisting of-OCH₃Radical, -OC₂H₅Radical and-OCOCH₃A compound having 2 to 4 hydrolyzable groups in the group. The silane coupling agent may contain a reactive group such as an amino group, an epoxy group, a vinyl group (allyl group), a methacryloyl group, a mercapto group, an isocyanate group, or a thioether group, or a methyl group, in addition to the hydrolyzable group.

Examples of the silane coupling agent include amino compounds such as 3- (2-aminoethylamino) propyldimethoxymethylsilane, 3- (2-aminoethylamino) propyltriethoxysilane, 3- (2-aminoethylamino) propyltrimethoxysilane, 3-aminopropyldiethoxymethylsilane, 3-aminopropyltriethoxysilane, and 3-aminopropyltrimethoxysilane, epoxy compounds such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyl (dimethoxy) methylsilane, and diethoxy (3-glycidoxypropyl) methylsilane, 3-acryloxypropyltrimethoxysilane, and the like, (meth) acrylates such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropylmethyldimethoxysilane and 3-methacryloxypropylmethyldiethoxysilane, vinyl compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, p-vinyltrimethoxysilane, diethoxymethylvinylsilane and vinyltris (2-methoxyethoxy) silane, allyl compounds such as allyltriethoxysilane and allyltrimethoxysilane, styryl compounds such as p-vinyltrimethoxysilane, isocyanates such as 3-isocyanatopropyltrimethoxysilane and 3-isocyanatopropyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc., and the like, Ureas such as 3-ureidopropyltriethoxysilane, (3-mercaptopropyl) triethoxysilane, (3-mercaptopropyl) trimethoxysilane, mercapto compounds such as, bis (triethoxysilylpropyl) tetrasulfide, tetraethyl orthosilicate, methyltrimethoxysilane, etc.

The photosensitive resin composition may contain melamine. In this case, the degree of corrosion of the cured product of the photosensitive resin composition by an oxidizing agent containing potassium permanganate, for example, can be significantly reduced. That is, when the surface of the cured product of the photosensitive resin composition is roughened in a step prior to the plating treatment by including melamine in the photosensitive resin composition, the thickness of the layer including the cured product can be made less likely to be thin. By providing a rough surface to the cured product in this manner, the adhesion between the cured product of the photosensitive resin composition and the plating layer made of copper, gold, or the like can be improved. Melamine is 2,4, 6-triamino-1, 3, 5-triazine, and is generally available from commercially available compounds. The melamine is preferably dispersed in the photosensitive resin composition so that the average particle diameter is 20 μm or less, preferably 15 μm or less. Since melamine is uniformly dispersed in the photosensitive resin composition, melamine is further easily coordinately bonded to a metal element. This can further improve the adhesion of the photosensitive resin composition. The lower limit of the average particle size of melamine is not particularly limited, and may be 0.01 μm or more. The average particle size of melamine is D in the state where melamine is dispersed in an uncured photosensitive resin composition by a laser diffraction particle size distribution measuring apparatus₅₀Is measured.

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

The photosensitive resin composition of the present embodiment may contain an organic solvent. The organic solvent is used for the purpose of liquefying or varnishing the photosensitive resin composition, adjusting viscosity, adjusting coatability, adjusting film formability, and the like.

The organic solvent may contain, for example, straight-chain, branched, dibasic or polyvalent alcohols selected from ethanol, propanol, isopropanol, hexanol, ethylene glycol and the like; ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene and xylene; petroleum aromatic mixed solvents such as Swasol series (manufactured by Wan petrochemical Co., Ltd.) and Solvesso series (manufactured by Exxon Chemical Co., Ltd.); cellosolves such as cellosolve and butyl cellosolve; carbitols 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, cellosolve acetate, carbitol acetate, etc.; and one or more compounds of dialkyl glycol ethers.

The carboxyl group-containing resin (a) is preferably in the range of 5 to 85 mass%, more preferably in the range of 10 to 75 mass%, and still more preferably in the range of 30 to 60 mass%, based on the solid content of the photosensitive resin composition. The solid content is the total amount of all components excluding volatile components such as a solvent from the photosensitive resin composition.

It is preferable that the unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule is in the range of 5 to 45% by mass relative to the carboxyl group-containing resin (a). When the unsaturated compound (B) is in this range, the through-hole 6 having the small diameter portion 63 can be easily produced. The unsaturated compound (B) is more preferably in the range of 10 to 42% by mass, still more preferably in the range of 21 to 40% by mass, based on the carboxyl group-containing resin (a).

The photopolymerization initiator (C) is preferably in the range of 1 to 30% by mass relative to the carboxyl group-containing resin (a). When the proportion of the photopolymerization initiator (C) is 1% by mass or more relative to the carboxyl group-containing resin (A), the photosensitive resin composition tends to have good light absorption. Since the photosensitive resin composition has good light absorption properties, the degree of curing of the surface of the interlayer insulating layer 7 is easily increased, and the water absorption properties of the interlayer insulating layer 7 can be reduced. In addition, the via hole 6 having the small diameter portion 63 is more easily formed in the interlayer insulating layer 7. If the photopolymerization initiator (C) is 30% by mass or less relative to the carboxyl group-containing resin (a), a cured film of the photosensitive resin composition tends to have good electrical insulation properties.

The photopolymerization initiator (C) is preferably in the range of 1.5 to 25% by mass, more preferably in the range of 2 to 20% by mass, still more preferably in the range of 3 to 10% by mass, based on the carboxyl group-containing resin (a).

When the photosensitive resin composition contains the epoxy resin (D), the total of the equivalents of epoxy groups contained in the epoxy resin (D) is preferably 0.1 to 5 relative to 1 equivalent of carboxyl groups of the carboxyl group-containing resin (a). Thermosetting properties can be imparted to the photosensitive resin composition by setting the equivalent of the epoxy group of the epoxy resin (D) to 0.1 or more relative to 1 equivalent of the carboxyl group-containing resin (a). When the epoxy group equivalent of the epoxy resin (D) is 5 or less with respect to the carboxyl group 1 equivalent of the carboxyl group-containing resin (a), the photosensitive resin composition has good developability. The epoxy group equivalent of the epoxy resin (D) is more preferably 0.3 to 4, still more preferably 0.5 to 3, and particularly preferably 0.7 to 2 relative to 1 equivalent of the carboxyl group-containing resin (A).

The content of the organic filler (E) is preferably 1 to 100% by mass based on the carboxyl group-containing resin (a). When the content of the organic filler (E) is 1 mass% or more, the surface of the cured product of the photosensitive resin composition can be appropriately roughened, and thus the adhesion between the roughened surface of the cured product and the plating layer can be improved. When the content of the organic filler (E) is 100% by mass or less, the photosensitive resin composition tends to have good developability. The content of the organic filler (E) is more preferably 1.5 to 50% by mass, still more preferably 2 to 30% by mass, and particularly preferably 3 to 20% by mass, based on the carboxyl group-containing resin (a). In this case, the through hole 6 having the small diameter portion 63 is particularly easily manufactured.

When the photosensitive resin composition contains a silane coupling agent, the content of the silane coupling agent is preferably 0.01 to 7% by mass relative to the organic filler (E). When the ratio of the silane coupling agent is in this range, the organic filler (E) in the photosensitive resin composition can be prevented from coagulating and the dispersibility can be improved. The proportion of the silane coupling agent is more preferably 0.05 to 5% by mass based on the organic filler (E). When the ratio of the silane coupling agent is in this range, the organic filler (E1) in the photosensitive resin composition can be more efficiently prevented from coagulating, and the dispersibility can be more effectively improved.

When the photosensitive resin composition contains melamine, the content of melamine is preferably 0.1 to 10% by mass relative to the carboxyl group-containing resin (a). At this time, the through-hole 6 having the small diameter portion 63 is more easily formed in the interlayer insulating layer 7 because the developing property with respect to the alkali aqueous solution is good. The content of melamine is more preferably 0.3 to 9% by mass, still more preferably 0.5 to 8% by mass, and particularly preferably 1 to 6% by mass, based on the carboxyl group-containing resin (a).

The proportion of the inorganic filler in the photosensitive resin composition can be appropriately set, and the content of the inorganic filler is preferably 0 to 200% by mass relative to the carboxyl group-containing resin (a). In this case, a good resolution can be obtained, and the via hole 6 having the small diameter portion 63 can be more easily formed in the interlayer insulating layer 7. The content of the inorganic filler is more preferably 0 to 150% by mass, still more preferably 0 to 100% by mass, yet more preferably 0 to 50% by mass, and particularly preferably 0 to 20% by mass, based on the carboxyl group-containing resin (a).

When the photosensitive resin composition contains an organic solvent, the amount of the organic solvent is preferably adjusted so that the organic solvent is rapidly volatilized when a coating film formed of the photosensitive resin composition is dried, that is, so that the organic solvent does not remain in the dried film. In particular, the proportion of the organic solvent is preferably 0 to 99.5% by mass, more preferably 15 to 60% by mass, based on the entire photosensitive resin composition. The preferable ratio of the organic solvent differs depending on the coating method and the like, and the ratio is preferably adjusted as appropriate depending on the 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 impaired.

The photosensitive resin composition may contain a blocked isocyanate selected from the group consisting of tolylene diisocyanate, morpholine diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate blocked with caprolactam, oxime, malonate and the like; butylated urea resin; various thermosetting resins other than those described above; ultraviolet-curable epoxy (meth) acrylate; resins obtained by adding (meth) acrylic acid to bisphenol a type, phenol novolac type, cresol novolac type, alicyclic type, and other epoxy resins; and at least one resin selected from the group consisting of diallyl phthalate resins, phenoxy resins, urethane resins, melamine resins, fluorine resins, and other high molecular weight compounds.

The photosensitive resin composition may contain a curing agent for curing the epoxy compound (D). The curing agent may contain, for example, imidazole derivatives selected from 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 the like; amine compounds such as dicyandiamide, benzyldimethylamine, 4- (dimethylamino) -N, N-dimethylbenzylamine, 4-methoxy-N, N-dimethylbenzylamine, and 4-methyl-N, N-dimethylbenzylamine; hydrazine compounds such as adipic dihydrazide and sebacic dihydrazide; phosphorus compounds such as triphenylphosphine; an acid anhydride; phenol; a thiol; a lewis acid amine complex; and

at least one component of a salt. Commercially available products of these components include, for example, 2MZ-A, 2MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (both trade names of imidazole compounds), U-CAT3503N manufactured by San-Apro corporation, UCAT3502T (both trade names of blocked isocyanate compounds of dimethylamine), DBU, DBN, U-CATSA102, and U-CAT5002 (both bicyclic amidine compounds and salts thereof).

The photosensitive resin composition may contain an adhesion-imparting agent. Examples of the adhesion imparting agent include 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), and s-triazine derivatives such as 2, 4-diamino-6-methacryloyloxyethyl-s-triazine, 2-vinyl-4, 6-diamino-s-triazine isocyanuric acid adduct, 2, 4-diamino-6-methacryloyloxyethyl-s-triazine isocyanuric acid adduct, silane coupling agents, melamine derivatives, and the like.

The photosensitive resin composition may contain a rheology control agent. The viscosity of the photosensitive resin composition can be easily optimized by the rheology control agent. Examples of the rheology control agent include urea-modified medium polarity polyamides (BYK-430 and BYK-431, product numbers of BYK Chemie Japan K.K.), polyhydroxycarboxylic acid amides (BYK-405, product number of BYK Chemie Japan K.K.), modified ureas (BYK-410, BYK-411, and BYK-420, product numbers of BYK Chemie Japan K.K.), high molecular urea derivatives (BYK-415, product number of BYK Chemie Japan K.K.), urea-modified urethanes (BYK-425, product number of BYK-Chemie Japan K.K.K.), polyurethanes (BYK-428, product number of BYK-Chemie Japan K.K.), castor oil waxes, polyethylene waxes, polyamide waxes, bentonite, kaolin, and clay.

The photosensitive resin composition may contain at least one component selected from the group consisting of a curing accelerator, a coloring agent, a copolymer such as silicone or acrylate, a leveling agent, a thixotropic agent, a polymerization inhibitor, an antihalation agent, a flame retardant, an antifoaming agent, an antioxidant, a surfactant, and a polymer dispersant.

The photosensitive resin composition of the present embodiment can be prepared by an appropriate method. For example, the photosensitive resin composition can be prepared by mixing and stirring raw materials of the photosensitive resin composition. The photosensitive resin composition can be prepared by kneading the components by an appropriate kneading method using, for example, a three-roll mill, a ball mill, a sand mill, or the like. When the raw materials contain a liquid component, a component having a low viscosity, or the like, the raw materials may be first kneaded except for the liquid component, the component having a low viscosity, or the like to prepare a mixture, and then the liquid component, the component having a low viscosity, or the like may be added to the obtained mixture and mixed to prepare the photosensitive resin composition. When the photosensitive resin composition contains the solvent (E), a part or all of the solvent in the raw materials may be first mixed, and then the mixture may be mixed with the remaining raw materials.

The photosensitive resin composition preferably has the following properties: even a coating film 4 having a thickness of 25 μm can be developed with an aqueous solution of sodium carbonate. In this case, since a sufficiently thick electrically insulating layer can be formed from the photosensitive resin composition by photolithography, the photosensitive resin composition can be widely used for forming the interlayer insulating layer 7 in the printed wiring board 11. Of course, an electrically insulating layer thinner than 25 μm may be formed from the photosensitive resin composition.

Whether or not the coating 4 having a thickness of 25 μm can be developed with an aqueous sodium carbonate solution can be confirmed by the following method. A wet coating film is prepared by applying a photosensitive resin composition to an appropriate substrate 1, and the wet coating film is heated at 80 ℃ for 40 minutes to form a coating film 4 having a thickness of 25 μm. A negative mask having an exposed part for transmitting ultraviolet rays and a non-exposed part for blocking ultraviolet rays is directly pressed against the coating film 4 at a thickness of 500mJ/cm²The coating 4 is exposed to ultraviolet light. After exposure, the coating 4 was sprayed with 1% Na at 30 ℃ under a spraying pressure of 0.2MPa₂CO₃After 90 seconds, the aqueous solution was treated by spraying pure water at a spray pressure of 0.2MPa for 90 seconds. After this treatment, the coating 4 was observed, and as a result, when the portion of the coating 4 corresponding to the non-exposed portion was removed and no residue was observed, it was judged that the coating 4 having a thickness of 25 μm could be developed with an aqueous sodium carbonate solution. It can be similarly confirmed whether or not the coating 4 having another thickness (for example, 30 μm) can be developed with the sodium carbonate aqueous solution.

(2.2) production of printed Wiring Board 11

A method for manufacturing printed wiring board 11 according to the present embodiment will be described with reference to fig. 1A to 1E.

In 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 overlapping the insulating layer 2. A coating film 4 made of a photosensitive resin composition is superposed on the substrate so as to cover the second conductor layer 3, and a negative pattern region including the pattern of the through hole 6 of the coating film 4 is exposed to light and then subjected to a development treatment 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, as shown in fig. 1A, a substrate 1 is prepared. The substrate 1 includes an insulating layer 2 and a second conductor layer 3. The second conductor layer 3 is a conductor wiring.

The photosensitive resin composition is applied to the substrate, and further dried as necessary, thereby producing a coating film 4 covering the second conductor layer 3 as shown in fig. 1B. The method for applying the photosensitive resin composition is selected from known methods, for example, dipping method, spraying method, spin coating method, roll coating method, curtain coating method, and screen printing method. When the photosensitive resin composition is dried, the photosensitive resin composition is heated at a temperature of, for example, 60 to 130 ℃.

The film 4 can be produced by laminating a dry film made of a photosensitive resin composition on a substrate. The dry film is formed on a suitable support made of, for example, polyester by applying the photosensitive resin composition to the support and then drying the applied composition. Thus, a dry film with a support having the dry film and a support for supporting the dry film can be obtained. After the dry film of the dry film with a support is superimposed on the substrate 1 so as to cover the second conductor layer 3, pressure is applied to the dry film and the substrate 1. Thus, the coating film 4 made of a dry film is superimposed on the substrate 1.

Next, the film 4 is exposed. For example, a negative pattern-like region including the pattern of the through-hole 6 of the film 4 is exposed. At this time, the coating 4 is irradiated with ultraviolet rays through a negative mask, for example. The negative mask includes an exposed portion that transmits ultraviolet rays and a non-exposed portion that blocks ultraviolet rays, and the pattern of the non-exposed portion includes the pattern of the through holes 6. The negative mask is, for example, an optical tool (photo tool) such as a mask film (mask film) or a dry plate. The light source of ultraviolet rays is selected from, for example, 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.

In the case of preparing the film 4 from a dry film, when the film 4 is exposed, for example, the support is peeled from the film 4 in advance, and then the film 4 is exposed. In a state where the support is superimposed on the film 4, the film 4 may be exposed by irradiating the film 4 with ultraviolet light through the support, and the support may be peeled off from the exposed film 4.

As the exposure method, a method other than the method using the negative mask may be employed. For example, the film 4 may be exposed by a direct writing method in which ultraviolet light emitted from a light source is irradiated only to a portion of the film 4 to be exposed. The light source applied to the direct writing method is selected from, for example, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, g-rays (436nm), h-rays (405nm), i-rays (365nm), and a combination of two or more of g-rays, h-rays, and i-rays.

The ultraviolet ray irradiated to the coating 4 preferably has a spectral intensity at least one wavelength in a wavelength region of 365nm ± 65 nm. The ultraviolet ray irradiated to the film 4 preferably does not have a spectral intensity at a wavelength of 435nm or more. The ultraviolet rays irradiated to the coating film 4 have a spectral intensity at least one wavelength in a wavelength region of 365nm ± 65nm, and thereby the coating film 4 is easily cured. In addition, if the ultraviolet rays include light having a wavelength of 435nm or more, the diameter of the second end 62 of the through hole 6 formed in the interlayer insulating layer 7 is likely to be reduced after development. This reason is presumably because light having a long wavelength of 435nm or more is not easily absorbed by the photosensitive resin composition and easily reaches the deep part of the film 4, and light is easily scattered in the deep part of the film 4. The ultraviolet ray irradiated to the film 4 preferably has a spectral intensity at least at one wavelength in a wavelength region of 365nm ± 45nm and no spectral intensity at 415nm or more, more preferably has a spectral intensity at least at one wavelength in a wavelength region of 365nm ± 30nm and no spectral intensity at 400nm or more, and particularly preferably has a spectral intensity at least at one wavelength in a wavelength region of 365nm ± 15nm and no spectral intensity at 385nm or more.

Next, the coating film 4 is developed with an alkaline aqueous solution to produce the interlayer insulating layer 7 having the through hole 6. At this time, as already described, the through hole 6 having the small diameter portion 63 is easily formed. The coating 4 is subjected to a developing treatment to remove the uncured portion 5 of the coating 4 shown in fig. 1C, thereby providing the through hole 6 as shown in fig. 1D. In the development treatment, an appropriate developer corresponding to the composition of the photosensitive resin composition may be used. The developer is, for example, an alkaline aqueous solution containing at least one of an alkali metal salt and an alkali metal hydroxide, or an organic amine. More specifically, the basic aqueous solution contains, for example, at least one component selected from the group consisting of sodium carbonate, potassium carbonate, ammonium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, ammonium hydrogen carbonate, sodium hydroxide, potassium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, and lithium hydroxide. The solvent in the alkaline aqueous solution may be water alone or a mixture of water and a hydrophilic organic solvent such as a lower alcohol. 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, the work environment can be improved and the burden of waste disposal can be reduced.

Since the photosensitive resin composition of the present embodiment has good developability, it is not easy for uncured residues of the photosensitive resin composition to remain at the bottom of the through hole 6 after development. Therefore, the through-hole 6 having the small diameter portion 63 is easily formed.

Subsequently, the developed coating film 4 can be thermally cured by heating. The heating conditions are, for example, a heating temperature in the range of 120 to 200 ℃ and a heating time in the range of 20 to 180 minutes. When the film 4 is thermally cured in this manner, the strength, hardness, chemical resistance, and other properties of the interlayer insulating layer 7 are improved.

If necessary, the film 4 may be further irradiated with ultraviolet rays either before or after heating or both. In this case, the film 4 can be further photocured.

In this way, the interlayer insulating layer 7 made of a cured product of the photosensitive resin composition is provided on the substrate 1. Next, the first conductor layer 8 as a conductor wiring may be formed on the interlayer insulating layer 7 by a known method such as an additive method, and the via conductor 9 may be formed in the through hole 6. As a result, as shown in fig. 1E, a printed wiring board 11 including the first conductor layer 8, the second conductor layer 3, the interlayer insulating layer 7, the through hole 6, and the via conductor 9 was obtained. In fig. 1E, the via conductor 9 is filled in the entire through hole 6, but the via conductor 9 may be a film covering the inner surface of the through hole 6.

Before the via conductor 9 is formed, the entire inner surface of the through hole 6 and a part of the outer surface of the interlayer insulating layer 7 may be roughened. In this case, the adhesion between the base 1 and the via 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 through-hole 6 may be performed in the same manner as in a 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, the roughening method is not limited thereto, and appropriate roughening methods such as plasma treatment, UV treatment, and ozone treatment may be used.

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

When the via conductor 9 is provided, an electroless metal plating treatment may be applied to a part of the roughened outer surface and the inner surface of the through-hole 6 to form an initial conductor. Thereafter, the metal in the plating solution is deposited to the initial conductor by electrolytic metal plating treatment, thereby forming the via conductor 9.

Examples

Hereinafter, the present disclosure will be specifically described by examples. However, the present disclosure is not limited to the following embodiments, and various modifications may be made in accordance with the design as long as the object of the present disclosure can be achieved.

1. Synthesis of carboxyl group-containing resin

[ Synthesis examples 1 to 6: resin having bisphenol fluorene skeleton ]

A mixture was prepared by charging the components shown in the column of "first reaction" in table 1 into a four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer, and stirring them under bubbling of air. The mixture was heated in a flask with stirring under bubbling of air at a reaction temperature and for a reaction time shown in the column of "reaction conditions". Thus, a solution of the intermediate was prepared.

Next, the components shown in the column "second reaction" in table 1 were put into the solution of the intermediate in the flask, and the mixture was heated at the reaction temperature and the reaction time shown in the column "reaction condition (1)" while stirring with bubbling air. Subsequently, the mixture was heated at the reaction temperature and the reaction time shown in the column of "reaction conditions (2)" while stirring the mixture under bubbling of air. Thus, a 65 mass% solution of the carboxyl group-containing resin was obtained. The weight average molecular weight and acid value of the carboxyl group-containing resin are shown in Table 1.

The details of the components shown in column (a1) in table 1 are as follows.

Epoxy compound 1: r in formula (2) and represented by formula (2)₁～R₈A bisphenol fluorene type epoxy compound having an epoxy equivalent of 250g/eq based on the total hydrogen.

Epoxy compound 2: r in formula (2) and represented by formula (2)₁And R₅Are both methyl and R₂～R₄And R₆～R₈A bisphenol fluorene type epoxy compound having an epoxy equivalent of 279g/eq each to hydrogen.

[ Synthesis example 7: resin containing bisphenol aldehyde varnish skeleton

288 parts by mass of a biphenyl novolak type epoxy resin (manufactured by Nippon Kasei Co., Ltd., product No. NC-3000-H, epoxy equivalent 288g/eq), 155 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 part by mass of methyl hydroquinone, 72 parts by mass of acrylic acid, and 3 parts by mass of triphenylphosphine were charged in a four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube, and a stirrer to prepare a mixture. The mixture was heated at a temperature of 115 ℃ for 12 hours in a flask while stirring with bubbling of air. Thus, a solution of the intermediate was prepared.

Then, 85 parts by mass of tetrahydrophthalic anhydride and 86.3 parts by mass of diethylene glycol monoethyl ether acetate were put into the intermediate solution in the flask, and the mixture was heated at 90 ℃ for 4 hours while stirring with bubbling of air. Thus, a 65% by mass solution of the 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. Preparation of the composition

The components shown in tables 2 to 3 described later were kneaded by a three-roll mill, and then stirred and mixed in a flask to obtain a composition. The components shown in tables 2 to 3 are described in detail below.

Unsaturated compound a: trimethylolpropane triacrylate.

Photopolymerization initiator a: 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, product number Irgacure TPO, from BASF.

Photopolymerization initiator B: 1-hydroxy-cyclohexyl-phenyl-ketone, product number Irgacure 184, from BASF.

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, product number YSLV-80XY manufactured by Nippon Temminck & Chemicals, melting point 75-85 ℃, epoxy equivalent 192 g/eq.

Amorphous epoxy resin solution a: a bisphenol A type epoxy resin having a long carbon chain (product number EPICLON EXA-4816, liquid resin, epoxy equivalent 410g/eq, available from DIC corporation) was dissolved in diethylene glycol monoethyl ether acetate to give a solution having a solid content of 90%.

Organic filler a dispersion: a dispersion (product No. XER-91-MEK, manufactured by JSR Corp., product No. XER-91-MEK; acid value: 10.0mgKOH/g) obtained by dispersing a crosslinked rubber (NBR) having an average primary particle diameter of 0.07 μm in methyl ethyl ketone in an amount of 15% by weight based on the total amount of the dispersion.

Organic filler B: glycidyl group-modified acrylonitrile butadiene rubber having an average primary particle diameter of 0.3. mu.m.

Additive A: 3-glycidoxypropyltrimethoxysilane.

Additive B: melamine.

Solvent a: methyl ethyl ketone.

3. Evaluation of the composition

(1) Production of test pieces

Test pieces were prepared as follows using the compositions of the respective composition examples.

The composition of each composition example was applied to a film made of polyethylene terephthalate by an applicator, heated at 80 ℃ for 5 minutes, and then heated at 95 ℃ for 20 minutes to dry the film, thereby forming a dry film having a thickness of 35 μm on the film.

A glass epoxy copper-clad laminate (FR-4 type) having a copper foil thickness of 17.5 μm was prepared. The surface portion of the glass epoxy copper-clad laminate having a thickness of about 1 μm was roughened by treatment with an etchant (product number CZ-8101 manufactured by MEC corporation). And laminating the dry film heating layer on the whole surface of one surface of the glass epoxy copper-clad laminated plate by using a vacuum laminating machine. The conditions for heat lamination were set to 0.5MPa, 80 ℃ and 1 minute. Thereby, a film composed of the dry film is formed on the glass epoxy copper-clad laminate. A cumulative light amount at 250mJ/cm through a negative mask having a non-exposed portion and a film made of polyethylene terephthalate²The coating was irradiated with ultraviolet rays having a wavelength of 365nm under the conditions described above, and the unexposed portion had a pattern including a circular shape having a diameter of 80 μm. Subsequently, the polyethylene terephthalate film was peeled off from the coating film.

Then, an aqueous alkaline solution (1% Na) at 30 ℃ was sprayed on the coating film at a spray pressure of 0.2MPa₂CO₃Aqueous solution) for 90 seconds, and then pure water was sprayed at a spray pressure of 0.2MPa for 90 seconds, thereby developing the coating. Subsequently, the film was heated at 180 ℃ for 120 minutes. Thereby forming interlayer insulation on the printed wiring boardA layer and a via hole penetrating the interlayer insulating layer. Thus, a test piece was obtained.

The test piece was evaluated as follows. In composition example 11, development was not possible and evaluation was not performed. Further, composition example 14 had a portion where peeling of the coating film due to insufficient curing was observed during development, and therefore was not evaluated.

(2) Determination of the diameter of the first end and the diameter of the second end

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

(3) Presence or absence of small diameter part

From the image obtained in the above "(2) measurement of the diameter of the first end and the diameter of the second end", whether or not a small diameter portion exists between the first end and the second end of the through hole is confirmed, and evaluation is performed as follows.

A: a small diameter portion is present between the first end and the second end, and a minimum diameter of the small diameter portion is 65% or more and less than 100% with respect to a diameter of the second end.

B: a small diameter portion exists between the first end and the second end, and a minimum diameter of the small diameter portion is less than 65% relative to a diameter of the second end.

C: there is no small diameter portion between the first end and the second end.

(4) Evaluation of via shape

The shape of the through-hole was evaluated as follows from the image obtained in the above "(2) measurement of the diameter of the first end and the diameter of the second end").

A: the value of (diameter of the first end ÷ diameter of the second end) × 100 (%) is 80% or more, and a small diameter portion having a diameter of 65% or more and less than 100% with respect to the second end is present between the first end and 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 a small diameter portion of 65% or more and less than 100% with respect to the diameter of the second end is present between the first end and 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 a small diameter portion having a diameter of 65% or more and less than 100% with respect to the second end is present between the first end and 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 above evaluation tests are shown in tables 2 to 3 below.

4. Evaluation of printed Wiring Board

(1) Production of test pieces

Test pieces were produced by the method described in "1. evaluation of composition" (1) production of test pieces "above, except that the method of forming a coating film, the thickness of the coating film, the diameter of a circular pattern during exposure, the wavelength and cumulative amount of ultraviolet light, and the ejection time of an alkaline aqueous solution during development were as shown in tables 4 to 6. When a plurality of numerical values are described in the column of the wavelength, ultraviolet rays having wavelengths of the respective numerical values are simultaneously irradiated.

The test piece was evaluated as follows. In comparative example 1, development was not possible and evaluation was not performed. In comparative example 3, the coating was not evaluated because a portion where peeling of the coating due to insufficient curing was observed during development.

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

(3) Presence or absence of small diameter part

C: there is no small diameter portion between the first end and the second end.

(4) Evaluation of via shape

E: there is no small diameter portion.

(5) Reliability of via connection

For the test piece, the outer surface of the interlayer insulation layer was roughened by a general desmear treatment described below as a pre-process of the plating treatment.

The interlayer insulating layer was subjected to Swelling treatment using a Swelling solution for desmearing (Swelling Dip securigant P manufactured by Atotech Japan corporation) at 70 ℃ for 10 minutes to swell the surface of the interlayer insulating layer, and then the interlayer insulating layer was washed with hot water. Next, the surface of the interlayer insulating layer was roughened by treating the surface with a desmear solution (center Compact CP containing potassium permanganate manufactured by Atotech Japan) at 70 ℃ for 10 minutes, and then the interlayer insulating layer was washed with hot water. Next, the surface of the interlayer insulating layer was treated with a neutralizing solution (Reduction solution securigantehp manufactured by Atotech Japan) at 40 ℃ for 5 minutes to remove the residue, and then the interlayer insulating layer was washed with water.

Next, an initial conductor was fabricated by performing electroless copper plating treatment on the interlayer insulating layer, and then heated at 150 ℃ for 1 hour. Then at a current density of 2A/dm²After electrolytic copper plating treatment was performed on the initial conductor, the conductor was heated at 180 ℃ for 30 minutes. Thus, a first conductor layer having a thickness of 33 μm was formed on the interlayer insulating layer, and a via conductor was formed in the through hole.

Next, the test piece was subjected to a 500-cycle temperature cycle test in which the test piece was exposed to-55 ℃ for 15 minutes and then to 125 ℃ for 15 minutes. The resistance value between the first conductor layer and the second conductor layer passing through the via conductor before and after the test was measured, and the rate of change thereof was evaluated as follows.

A: the rate of change in resistance values before and after the temperature cycle test was less than 8%.

B: the rate of change in resistance value before and after the temperature cycle test is 8% or more and less than 10%.

C: the rate of change in resistance value before and after the temperature cycle test is 10% or more.

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

[ Table 1]

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

Claims

1. 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 via conductor disposed in the through hole and electrically connecting the first conductor layer and the second conductor layer,

the interlayer insulating layer 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 has a first end, a second end, and a small diameter portion, the first end being an end on the first conductor layer side, the second end being an end on the second conductor layer side, the small diameter portion being located between the first end and the second end and having a diameter smaller than a diameter of the second end.

2. The printed wiring board according to claim 1, wherein a minimum diameter of the small diameter portion is 65% or more and less than 100% of a diameter of the second end.

3. The printed wiring board according to claim 1 or 2, wherein the diameter of the first end is 65% or more with respect to the diameter of the second end.

4. The printed wiring board according to any one of claims 1 to 3, wherein the diameter of the first end is 100 μm or less.

5. The printed wiring board according to any one of claims 1 to 4, wherein the carboxyl group-containing resin A contains a carboxyl group-containing resin A1 having a bisphenol fluorene skeleton.

6. The printed wiring board according to any one of claims 1 to 5, wherein the carboxyl group-containing resin A has a weight average molecular weight of 700 to 100000.

7. The printed wiring board according to any one of claims 1 to 6, wherein the carboxyl group-containing resin A contains a component having an acid value of 65mgKOH/g to 150 mgKOH/g.

8. The printed wiring board according to any one of claims 1 to 7, wherein the percentage of the unsaturated compound B with respect to the carboxyl group-containing resin A is 5 to 45 mass%.

9. The printed wiring board according to any one of claims 1 to 8, wherein the percentage of the photopolymerization initiator C with respect to the carboxyl group-containing resin A is 1 to 30% by mass.

10. The printed wiring board according to any one of claims 1 to 9, wherein the photopolymerization initiator C contains at least one selected from an acylphosphine oxide-based photopolymerization initiator, an α -aminoalkylphenone-based photopolymerization initiator, and an oxime ester-based photopolymerization initiator.

11. The printed wiring board according to any one of claims 1 to 10, wherein the photosensitive resin composition further contains an epoxy resin D.

12. The printed wiring board according to claim 11, wherein the epoxy group equivalent of the epoxy resin D is 0.1 to 5 relative to 1 equivalent of the carboxyl group-containing resin A.

13. The printed wiring board according to any one of claims 1 to 12, wherein the photosensitive resin composition further contains an organic filler E.

14. The printed wiring board of claim 13, wherein the organic filler E has a reactive group.

15. The printed wiring board according to claim 14, wherein the reactive group comprises at least one group selected from a carboxyl group, an amino group, an epoxy group, a vinyl group, and a hydroxyl group.

16. The printed wiring board according to any one of claims 13 to 15, wherein the proportion of the organic filler E to the carboxyl group-containing resin a is 1% by mass to 100% by mass.

17. A method of manufacturing a printed wiring board, which is the method of manufacturing the printed wiring board according to any one of claims 1 to 16, comprising:

preparing a negative photosensitive resin composition containing the carboxyl group-containing resin A, an unsaturated compound B having at least one ethylenically unsaturated bond in one molecule, and the photopolymerization initiator C, and a substrate having an insulating layer and the second conductor layer overlapping the insulating layer,

a coating film made of the photosensitive resin composition is superimposed on the substrate so as to cover the second conductor layer,

the interlayer insulating layer and the via hole penetrating the interlayer insulating layer are formed by exposing a negative pattern region of the film including the via hole pattern to light and then performing a development treatment using an alkaline aqueous solution.

18. The method of manufacturing a printed wiring board according to claim 17, comprising forming the coating film by superimposing a dry film formed of the photosensitive resin composition on the substrate.

19. The method for manufacturing a printed wiring board according to claim 17 or 18, wherein, when exposing the coating film, the coating film is irradiated with light having a spectral intensity at least one wavelength located in a wavelength region of 365nm ± 65nm and having no spectral intensity at a wavelength of 435nm or more.