CN110999554B

CN110999554B - Method for manufacturing multilayer printed wiring board and multilayer printed wiring board

Info

Publication number: CN110999554B
Application number: CN201880051661.3A
Authority: CN
Inventors: 樋口伦也; 藤原勇佐; 田中信也; 铃木文人; 桥本壮一; 荒井贵
Original assignee: Goo Chemical Industries Co Ltd
Current assignee: Goo Chemical Industries Co Ltd
Priority date: 2017-08-09
Filing date: 2018-08-01
Publication date: 2021-05-18
Anticipated expiration: 2038-08-01
Also published as: TWI722308B; WO2019031322A1; KR20200035008A; JP6705084B2; TW201910137A; JPWO2019031322A1; CN110999554A; KR102189000B1

Abstract

The invention provides a method for manufacturing a multilayer printed wiring board, which can realize high adhesion between an interlayer insulating layer and a conductor layer even if the interlayer insulating layer is not roughened or the degree of roughening is small. A method for manufacturing a multilayer printed wiring board (20) includes the steps of forming a coating film (4) on a printed wiring board (1) from a photosensitive resin composition, photocuring the coating film to form a cured film (11), treating the cured film (11) with an alkaline solution, and then forming a conductor layer (8). The photosensitive resin composition contains a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, a photopolymerization initiator (C), and an epoxy compound (D). The arithmetic mean roughness Ra of the surface of the cured film (11) in contact with the conductor layer (8) immediately before the conductor layer (8) is formed is less than 150 nm.

Description

Method for manufacturing multilayer printed wiring board and multilayer printed wiring board

Technical Field

The present invention relates to a method for manufacturing a multilayer printed wiring board and a multilayer printed wiring board.

Background

Conventionally, an electrically insulating resin composition has been used for producing electrically insulating layers such as solder resist layers, plating resist layers, etching resist layers, and interlayer insulating layers of printed wiring boards. Such a resin composition is, for example, a photosensitive resin composition (see patent document 1).

In particular, when an interlayer insulating layer is formed from a photosensitive resin composition, the interlayer insulating layer is roughened in order to ensure adhesion between the interlayer insulating layer and a conductor layer formed thereon by plating or the like (see patent document 1). When the interlayer insulating layer is roughened, the high-frequency characteristics of the printed wiring board are deteriorated, and therefore, the transmission characteristics of high-speed signals of the printed wiring board are deteriorated.

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 11-242330

Disclosure of Invention

The invention aims to provide a method for manufacturing a multilayer printed wiring board and the multilayer printed wiring board, which can realize high adhesion between an interlayer insulating layer and a conductor layer even if the interlayer insulating layer is not roughened or the degree of roughening is small.

In the method for manufacturing a multilayer printed wiring board according to one embodiment of the present invention, a coating film is formed on the printed wiring board from the photosensitive resin composition. The photosensitive resin composition contains a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, a photopolymerization initiator (C), and an epoxy compound (D). The cured film is produced by photocuring the coating film. The cured film is treated with an alkaline solution to prepare a conductor layer in contact with the cured film. The surface of the cured film in contact with the conductor layer immediately before the conductor layer is formed has an arithmetic average roughness Ra of less than 150nm, as defined in JIS B0601-2001.

The multilayer printed wiring board according to one embodiment of the present invention is produced by the above-described production method.

Drawings

Fig. 1A to 1E in fig. 1 are sectional views showing a process of manufacturing a multilayer printed wiring board.

Detailed Description

The following embodiments relate to a method for manufacturing a multilayer printed wiring board and a multilayer printed wiring board manufactured by the manufacturing method, and more particularly, to a method for manufacturing a multilayer printed wiring board in which a cured film of a photosensitive resin composition is formed on a printed wiring board, and a multilayer printed wiring board manufactured by the manufacturing method.

Hereinafter, one embodiment of the present invention will be described. In the following description, "(meth) acrylic acid" represents at least one of "acrylic acid" and "methacrylic acid". For example, (meth) acrylate means at least one of acrylate and methacrylate.

In the method for manufacturing the multilayer printed wiring board 20 of the present embodiment (see fig. 1A to 1E), the coating film 4 is formed on the printed wiring board 1 from the photosensitive resin composition. The photosensitive resin composition contains a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, a photopolymerization initiator (C), and an epoxy compound (D). The coating film 4 is photocured to produce a cured film 11. The cured film 11 is treated with an alkaline solution, and then the conductor layer 8 in contact with the cured film 11 is formed. The arithmetic mean roughness Ra specified in JIS B0601-2001 of the surface of the cured film 11 in contact with the conductor layer 8 immediately before the conductor layer 8 is formed is less than 150 nm.

In the present embodiment, since the arithmetic mean roughness Ra of the cured film 11 is less than 150nm, even if the conductor layer 8 is formed in contact with the cured film 11, it is possible to suppress deterioration of the high-frequency characteristics of the multilayer printed wiring board 20 and to maintain the high-speed signal transmission characteristics of the multilayer printed wiring board 20 satisfactorily.

Furthermore, by treating the cured film 11 with an alkaline solution, the adhesion between the interlayer insulating layer 7 composed of the cured film 11 and the conductor layer 8 can be improved. The reason for this is not sufficiently clear, but it is considered that when the cured film 11 is treated with an alkali solution, fine irregularities are generated although the surface of the cured film 11 is not roughened greatly, and this is one factor for improving the adhesion between the interlayer insulating layer 7 and the conductor layer 8.

Therefore, even if the interlayer insulating layer 7 is not roughened or the degree of roughening is small, high adhesion between the interlayer insulating layer 7 and the conductor layer 8 can be achieved.

The photosensitive resin composition used in the present embodiment will be described in detail.

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, the photopolymerization initiator (C), and the epoxy compound (D).

The carboxyl group-containing resin (A) preferably contains a carboxyl group-containing resin having an ethylenically unsaturated group. In this case, the carboxyl group-containing resin (a) can have photoreactivity. Therefore, the carboxyl group-containing resin (a) can impart photosensitivity, specifically ultraviolet curability, to the photosensitive resin composition.

The carboxyl group-containing resin (a) preferably contains a carboxyl group-containing resin having an aromatic ring. In this case, a cured product of the photosensitive resin composition can be provided with high heat resistance and high insulation reliability.

The carboxyl group-containing resin (a) more preferably contains a carboxyl group-containing resin having a polycyclic aromatic ring having any one of a biphenyl skeleton, a naphthalene skeleton, a fluorene skeleton and an anthracene skeleton. In this case, higher heat resistance and insulation reliability can be imparted to the cured product of the photosensitive resin composition.

The carboxyl group-containing resin (a) preferably contains a carboxyl group-containing resin (a1) having a bisphenol fluorene skeleton. In this case, higher heat resistance and insulation reliability can be imparted to the cured product of the photosensitive resin composition containing the carboxyl group-containing resin (a).

The carboxyl group-containing resin (a1) is, for example, a reactant of an intermediate, which is a reactant of an epoxy compound (a1) and a carboxylic acid (a2) containing an unsaturated group, with an acid dianhydride (a3) and an acid monoanhydride (a 4). The epoxy compound (a1) has a bisphenol fluorene skeleton. The bisphenol fluorene skeleton is represented by the following formula (1), wherein R in the formula (1)₁～R₈Each independently hydrogen, carbonAn alkyl group having 1 to 5 atoms or a halogen.

R in the formula (1)₁～R₈Each of which may be hydrogen, or an alkyl group having 1 to 5 carbon atoms or a halogen. The reason for this is that: 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 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.

When the carboxyl group-containing resin (a1) has a bisphenol fluorene skeleton derived from the epoxy compound (a1), high heat resistance and high insulation reliability can be imparted to a cured product of the photosensitive resin composition containing the carboxyl group-containing resin (a 1).

The carboxyl group-containing resin (a1) will be described more specifically. To synthesize the carboxyl group-containing resin (a1), first, an intermediate is synthesized by reacting at least a part of the epoxy groups in the epoxy compound (a1) having a bisphenol fluorene skeleton represented by formula (1) with a carboxylic acid (a2) containing an unsaturated group-containing carboxylic acid (a 2-1). The synthesis of the intermediate is specified as the first reaction. The intermediate has a secondary hydroxyl group generated by a ring-opening addition reaction of an epoxy group and a carboxylic acid (a2) comprising an unsaturated group-containing carboxylic acid (a 2-1). Next, the secondary hydroxyl group in the intermediate is reacted with an acid anhydride (a 3). Thereby, a carboxyl group-containing resin (a1) can be synthesized. The reaction of the intermediate with the acid anhydride (a3) is defined as the second reaction. The acid anhydride (a3) may comprise an acid monoanhydride and an acid dianhydride. The acid monoanhydride refers to a compound having one acid anhydride group obtained by dehydration condensation of two carboxyl groups in one molecule. The acid dianhydride is a compound having two acid anhydride groups obtained by dehydration condensation of four carboxyl groups in one molecule.

The carboxyl group-containing resin (a1) may contain unreacted components in the intermediate. When the acid anhydride (A3) includes the monoanhydride and the acid dianhydride, the carboxyl group-containing resin (a1) may include one or both of a reaction product of the component in the intermediate and the component in the monoanhydride and a reaction product of the component in the intermediate and the component in the acid dianhydride, in addition to the reaction products of the component in the intermediate and the component in the monoanhydride and the component in the acid dianhydride. That is, the carboxyl group-containing resin (a1) may be a mixture containing a plurality of compounds having different structures.

The carboxyl group-containing resin (A1) has photoreactivity by having an ethylenically unsaturated group derived from the unsaturated group-containing carboxylic acid (a 2-1). Therefore, the carboxyl group-containing resin (a1) can impart photosensitivity, specifically ultraviolet curability, to the photosensitive resin composition. The carboxyl group-containing resin (a1) has a carboxyl group derived from an acid anhydride (a3), and can impart developability to the photosensitive resin composition with an alkaline aqueous solution containing at least one of an alkali metal salt and an alkali metal hydroxide.

The weight average molecular weight of the carboxyl group-containing resin (A1) is preferably in the range of 700 to 10000. When the weight average molecular weight is 700 or more, the insulation property of the cured product of the photosensitive resin composition can be improved, and the dielectric loss tangent can be reduced. When the weight average molecular weight is 10000 or less, the developability of the photosensitive resin composition with an alkaline aqueous solution is particularly improved. The weight average molecular weight is more preferably 900 or more, and particularly preferably 1000 or more. The weight average molecular weight is more preferably 8000 or less, particularly preferably 5000 or less.

The polydispersity of the carboxyl group-containing resin (A1) is preferably in the range of 1.0 to 4.8. In this case, it is possible to ensure good insulation of a cured product formed from the photosensitive resin composition, and to impart excellent developability to the photosensitive resin composition. The polydispersity of the carboxyl group-containing resin (A1) is more preferably 1.1 to 4.0, and still more preferably 1.2 to 2.8.

The number average molecular weight and molecular weight distribution of the carboxyl group-containing resin (a1) can be achieved by suitably mixing the carboxyl group-containing resin (a1) with various components such as unreacted components in the intermediate, reactants of the components in the intermediate with the components in the acid monoanhydride and the components in the acid dianhydride, reactants of the components in the intermediate with the components in the acid monoanhydride, and reactants of the components in the intermediate with the components in the acid dianhydride. More specifically, it can be achieved by controlling parameters such as the average molecular weight of the epoxy compound (a1), the amount of acid monoanhydride with respect to the epoxy compound (a1), and the amount of acid dianhydride with respect to the epoxy compound (a1), for example.

The polydispersity is a value (Mw/Mn) of a ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of the carboxyl group-containing resin (a 1).

The solid acid value of the carboxyl group-containing resin (A1) is preferably in the range of 60mgKOH/g to 140 mgKOH/g. In this case, the developability of the photosensitive resin composition is particularly improved. The acid value is more preferably in the range of 80 to 135mgKOH/g, and still more preferably in the range of 90 to 130 mgKOH/g.

The molecular weight of the carboxyl group-containing resin (a1) can be adjusted by crosslinking of an acid dianhydride. In this case, a carboxyl group-containing resin (a1) having an adjusted acid value and molecular weight was obtained. That is, the molecular weight and acid value of the carboxyl group-containing resin (a1) can be easily adjusted by controlling the amount of acid dianhydride contained in the acid anhydride (A3). The molecular weight of the carboxyl group-containing resin (a1) was calculated from the measurement results by gel permeation chromatography under the following conditions.

GPC apparatus: shodex System 11 manufactured by Showa Denko K.K.,

column: the 4 SHODEX KF-800P, KF-005, KF-003 and KF-001 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 reaction conditions for synthesizing the raw material of the carboxyl group-containing resin (a1) and the carboxyl group-containing resin (a1) will be described in detail.

The epoxy compound (a1) has a structure represented by, for example, 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 particularly preferably in the range of 0 to 1. When the average value of n is in the range of 0 to 1, even when the acid anhydride (a3) contains an acid dianhydride, an excessive increase in molecular weight is easily suppressed.

The carboxylic acid (a2) contains an unsaturated group-containing carboxylic acid (a 2-1). The carboxylic acid (a2) may contain only the carboxylic acid (a 2-1) containing an unsaturated group. Alternatively, the carboxylic acid (a2) may contain both the carboxylic acid (a 2-1) having an unsaturated group and a carboxylic acid other than the carboxylic acid (a 2-1) having an unsaturated group.

The unsaturated group-containing carboxylic acid (a 2-1) may contain, for example, a compound having only one ethylenically unsaturated group. More specifically, the unsaturated group-containing carboxylic acid (a 2-1) may contain, for example, a compound selected from 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-acryloxypropylphthalic acid, 2-methacryloxypropylphthalic acid, 2-acryloxyethyl maleic acid, 2-methacryloxyethyl maleic acid, β -carboxyethyl acrylate, 2-acryloxyethyl tetrahydrophthalic acid, 2-methacryloxyethyl tetrahydrophthalic acid, 2-acryloxyethyl hexahydrophthalic acid, and 2-methacryloxyethyl hexahydrophthalic acid. It is preferable that the unsaturated group-containing carboxylic acid (a 2-1) contains acrylic acid.

The carboxylic acid (a2) may comprise a polyacid (a 2-2). The polybasic acid (a 2-2) is an acid in which 2 or more hydrogen atoms can be substituted with a metal atom in 1 molecule. The polybasic acid (a 2-2) preferably has 2 or more carboxyl groups. In this case, the epoxy compound (a1) reacts with both the unsaturated group-containing carboxylic acid (a 2-1) and the polybasic acid (a 2-2). The molecular weight is increased by crosslinking the polybasic acid (a 2-1) with the epoxy groups present in 2 molecules of the epoxy compound (a 1). This can improve the insulating properties of the cured product of the photosensitive resin composition and can reduce the dielectric loss tangent.

The polybasic acid (a 2-2) preferably comprises a dicarboxylic acid. The polybasic acid (a 2-2) may contain, for example, at least one compound selected from the group consisting of 4-cyclohexene-1, 2-dicarboxylic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, and terephthalic acid. Preferably, the polybasic acid (a 2-2) contains 4-cyclohexene-1, 2-dicarboxylic acid.

When the epoxy compound (a1) is reacted with the carboxylic acid (a2), a known method can be used. For example, a reactive solution is obtained by adding a carboxylic acid (a2) to a solvent solution of an epoxy compound (a1), and further adding a thermal polymerization inhibitor and a catalyst as needed, followed by stirring and mixing. The intermediate is obtained by reacting the reactive solution at a temperature of preferably 60 to 150 c, particularly preferably 80 to 120 c, by a conventional method. The solvent may contain at least one member selected from ketones such as methyl ethyl ketone and cyclohexanone, aromatic hydrocarbons such as toluene and xylene, and acetates and dialkyl glycol ethers such as ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, diethylene glycol monoethyl ether acetate and propylene glycol monomethyl ether acetate. The thermal polymerization inhibitor contains at least one of hydroquinone and hydroquinone monomethyl ether, for example. The catalyst may contain at least one component selected from tertiary amines such as benzyldimethylamine 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) and the carboxylic acid (a2) are preferably reacted in the presence of triphenylphosphine. In this case, the ring-opening addition reaction of the epoxy group in the epoxy compound (a1) and the carboxylic acid (a2) can be particularly promoted, and a reaction rate (conversion rate) of 95% or more, 97% or more, or almost 100% can be achieved. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive resin composition is suppressed, and the insulation property of the layer containing the cured product is improved.

The amount of the carboxylic acid (a2) in 1 mole of the epoxy group of the epoxy compound (a1) when the epoxy compound (a1) and the carboxylic acid (a2) are reacted is preferably in the range of 0.5 to 1.2 moles. In this case, excellent photosensitivity and stability of the photosensitive resin composition can be obtained. From the same viewpoint, the amount of the unsaturated group-containing carboxylic acid (a 2-1) is preferably in the range of 0.5 mol to 1.2 mol relative to 1 mol of the epoxy group of the epoxy compound (a 1). Alternatively, when the carboxylic acid (a2) includes a carboxylic acid other than the unsaturated group-containing carboxylic acid (a 2-1), the amount of the unsaturated group-containing carboxylic acid (a 2-1) may be in the range of 0.5 mol to 0.95 mol with respect to 1 mol of the epoxy group of the epoxy compound (a 1). When the carboxylic acid (a2) contains the polybasic acid (a 2-2), the amount of the polybasic acid (a 2-2) is preferably in the range of 0.025 mol to 0.25 mol based on 1 mol of the epoxy group of the epoxy compound (a 1). In this case, excellent photosensitivity and stability of the photosensitive resin composition can be obtained.

It is also preferable to react the epoxy compound (a1) with the carboxylic acid (a2) under air bubbling. In this case, the addition polymerization reaction of the unsaturated group can be suppressed, and the increase in 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 intermediate thus obtained has a hydroxyl group generated by the reaction of the epoxy group in the epoxy compound (a1) and the carboxyl group in the carboxylic acid (a 2).

The acid anhydride (a3) preferably comprises an acid monoanhydride. Acid monoanhydrides are compounds having one anhydride group.

The acid monoanhydride may contain an anhydride of a dicarboxylic acid. The acid monoanhydride may contain, for example, at least one compound selected from the group consisting of 1,2,3, 6-tetrahydrophthalic anhydride, phthalic anhydride, succinic anhydride, methylsuccinic anhydride, maleic anhydride, citraconic anhydride, glutaric anhydride, itaconic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, cyclohexane-1, 2, 4-tricarboxylic-1, 2-anhydride, and methylhexahydrophthalic anhydride. The acid monoanhydride particularly preferably comprises 1,2,3, 6-tetrahydrophthalic anhydride. In this case, the insulating property of the cured product of the photosensitive resin composition can be improved while ensuring good developability of the photosensitive resin composition. 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 acid monoanhydride, but is not limited thereto.

The acid anhydride (a3) preferably comprises an acid dianhydride. Acid dianhydrides are compounds having two anhydride groups. The acid dianhydride may contain an anhydride of a tetracarboxylic acid. The acid dianhydride may contain at least one compound 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 bistrimellitic acid anhydride monoacetate, ethylene glycol bistrimellitic anhydride, 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 ', 4,4 ' -biphenyltetracarboxylic acid dianhydride, for example. The acid dianhydride preferably contains an acid dianhydride having an aromatic ring. Particularly preferably, the acid dianhydride contains 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride. In this case, the insulating property of the cured product of the photosensitive resin composition can be improved while ensuring good developability of the photosensitive resin composition. In addition, the transparency of the photosensitive resin composition is improved, and the resolution is improved accordingly. The amount of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride is preferably in the range of 20 to 100 mol%, more preferably 40 to 100 mol%, based on the whole acid dianhydride, but is not limited thereto.

When the intermediate is reacted with the acid anhydride (a3), a known 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 added and mixed with stirring to obtain a reactive solution. The carboxyl group-containing resin (A1) is obtained by reacting the reactive solution by a conventional method at a temperature of preferably 60 to 150 ℃ and particularly preferably 80 to 120 ℃. As the solvent, the catalyst and the polymerization inhibitor, an appropriate solvent, catalyst and polymerization inhibitor may be used, or a solvent, catalyst and polymerization inhibitor used in the synthesis of an intermediate may be used as they are.

The catalyst particularly preferably contains triphenylphosphine. That is, the intermediate is preferably reacted with the acid anhydride (a3) in the presence of triphenylphosphine. In this case, the reaction between the secondary hydroxyl group of the intermediate and the acid anhydride (a3) can be particularly promoted, and a reaction rate (conversion rate) of 90% or more, 95% or more, 97% or more, or almost 100% can be achieved. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive resin composition is suppressed, and the insulation property of the layer containing the cured product is further improved.

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

The carboxyl group-containing resin (a) may contain a carboxyl group-containing resin having an aromatic ring and having no photopolymerization property. The carboxyl group-containing resin having an aromatic ring and not having photopolymerization properties is, for example, a polymer containing 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, ω -carboxy-polycaprolactone (n ≈ 2) monoacrylate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxyethyl-2-hydroxyethyl phthalate, and the like. 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 a linear or branched aliphatic or alicyclic (meth) acrylate (in which an unsaturated bond may be partially present in the ring).

The carboxyl group-containing resin (a) may contain a resin other than the carboxyl group-containing resin (a1), that is, a carboxyl group-containing resin having no 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 no photopolymerization property (hereinafter referred to as a (a 2-1) component). 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 linear or branched aliphatic or alicyclic (meth) acrylate (wherein the ring may have an unsaturated bond in some parts thereof).

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 (a 2-2) contains, for example, a resin (referred to as a first resin (x)) which is a reactant of an intermediate and at least one compound (x3) selected from a polycarboxylic acid and an acid anhydride thereof, and the intermediate is a reactant of an epoxy compound (x1) having two or more epoxy groups in one molecule and an ethylenically unsaturated compound (x 2). 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) and 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 extent to which the cured product of the photosensitive resin composition is significantly corroded by an oxidizing agent containing potassium permanganate, for example, can be reduced. The epoxy compound (x1) may contain a polymer of an ethylenically unsaturated compound (z). The ethylenically unsaturated compound (z) contains, for example, a compound (z1) having an epoxy group such as glycidyl (meth) acrylate, 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 (a 2-2) component may contain a resin (referred to as a second resin (y)) which is a reaction product of a polymer of an ethylenically unsaturated monomer containing an ethylenically unsaturated compound having a carboxyl group and an ethylenically unsaturated compound having an epoxy group. The ethylenically unsaturated monomer may further contain an ethylenically unsaturated compound 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 linear or branched aliphatic or alicyclic (wherein, in the ring, an unsaturated bond may be partially present) acrylates. 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). In order to obtain high transparency of the photosensitive resin composition and to reduce the dielectric loss tangent of a cured product of the photosensitive resin composition, the carboxyl group-containing resin (a) preferably contains 30% by mass or more of the carboxyl group-containing resin (a1), more preferably 60% by mass or more, and still more preferably 100% by mass.

The content of 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%, further preferably in the range of 26 to 60 mass%, and particularly preferably in the range of 30 to 45 mass% with respect to the solid content of the photosensitive resin composition. The solid content is the total amount of all components obtained by removing volatile components such as a solvent from the photosensitive resin composition.

The solid acid value of the carboxyl group-containing resin (A) is preferably in the range of 40mgKOH/g to 160 mgKOH/g. In this case, the stability of the photosensitive resin composition is particularly improved. The acid value is more preferably in the range of 60mgKOH/g to 140mgKOH/g, still more preferably in the range of 80mgKOH/g to 135mgKOH/g, and particularly preferably in the range of 90mgKOH/g to 130 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.

The unsaturated compound (B) is particularly preferably 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 when exposed and developed is improved, and the developability of the photosensitive resin composition by 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 cured product of the photosensitive resin composition has improved flame retardancy. The phosphorus-containing unsaturated compound may contain, for example, a compound selected from the group consisting of 2-methacryloyloxyethyl acid phosphate (specifically, model Nos. LIGHT ESTER P-1M and LIGHT ESTER P-2M manufactured by Kyoeisha chemical Co., Ltd.), 2-acryloxyethyl acid phosphate (specifically, model No. LIGHT ACRYLATE P-1A manufactured by Kyoeisha chemical Co., Ltd.), diphenyl-2-methacryloyloxyethyl phosphate (specifically, model No. MR-260 manufactured by Daba Industrial Co., Ltd.), and HFA series (specifically, model Nos. HFA-6003 and HFA-6007, which are addition products of dipentaerythritol hexaacrylate and HCA (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), caprolactone-modified dipentaerythritol hexaacrylate and HCA (9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) of the reaction product of the reaction.

The unsaturated compound (B) may contain a prepolymer. The prepolymer may contain 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 (meth) acrylate, for example.

The photopolymerization initiator (C) contains, for example, an acylphosphine oxide photopolymerization initiator. That is, the photosensitive resin composition contains, for example, an acylphosphine oxide photopolymerization initiator. In this case, when the photosensitive resin composition is exposed to ultraviolet light, high photosensitivity can be imparted to the photosensitive resin composition. In addition, the occurrence of ion migration in the layer containing the cured product of the photosensitive resin composition is suppressed, and the insulation reliability of the layer is further improved.

In addition, the acylphosphine oxide photopolymerization initiator does not easily inhibit the electrical insulation of the cured product. Therefore, by exposing and curing the photosensitive resin composition, a cured product having excellent electrical insulation properties can be obtained, and the cured product is suitable as the interlayer insulating layer 7.

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-phenylphosphonite 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, 4, 4-trimethylpentylphosphine oxide, bis- (2, 6-dimethoxybenzoyl) -2, 5-dimethylphenylphosphine oxide, bis (2, 6-dimethoxybenzoyl) -2, at least one component selected from bisacylphosphine oxide-based photopolymerization initiators such as bis- (2,4, 6-trimethylbenzoyl) phenylphosphine oxide and (2,5, 6-trimethylbenzoyl) -2, 4, 4-trimethylpentylphosphine oxide. Particularly preferably, the acylphosphine oxide-based photopolymerization initiator contains 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide, and further preferably, the acylphosphine oxide-based photopolymerization initiator contains only 2,4, 6-trimethylbenzoyl-diphenyl-phosphine oxide.

The photopolymerization initiator (C) preferably contains a hydroxyketone photopolymerization initiator in addition to the acylphosphine oxide photopolymerization initiator. That is, the photosensitive resin composition preferably contains a hydroxyketone photopolymerization initiator. In this case, higher photosensitivity can be imparted to the photosensitive resin composition than in the case where the hydroxyketone photopolymerization initiator is not contained. Thus, when a coating film formed from the photosensitive resin composition is cured by irradiation with ultraviolet rays, the coating film can be sufficiently cured from the surface to the deep part thereof. Examples of the hydroxyketone photopolymerization initiator include 1-hydroxy-cyclohexyl-phenyl ketone, methyl phenylglyoxylate, 1- [ 4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- { 4- [ 4- (2-hydroxy-2-methyl-propionyl) -benzyl ] phenyl } -2-methyl-propan-1-one, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one.

The mass ratio of the acylphosphine oxide-based photopolymerization initiator to the hydroxyketone-based photopolymerization initiator is preferably 1: 0.01-1: 10, in the range of 10. In this case, the curing property in the vicinity of the surface of the coating film formed of the photosensitive resin composition and the curing property in the deep portion can be improved in a good balance. Here, since 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 good developability cannot be obtained from the photosensitive resin composition arises. From such a viewpoint, in order to improve resolution and obtain good developability of the photosensitive resin composition, the mass ratio of the acylphosphine oxide-based photopolymerization initiator to the hydroxyketone-based photopolymerization initiator is particularly preferably in the range of 1: 0.01-1: 1, in the above range.

The photopolymerization initiator (C) preferably further contains a photopolymerization initiator having a benzophenone skeleton. That is, the photosensitive resin composition preferably further contains an acylphosphine oxide-based photopolymerization initiator and a photopolymerization initiator having a benzophenone skeleton, or contains an acylphosphine oxide-based photopolymerization initiator, a hydroxyketone-based photopolymerization initiator and a photopolymerization initiator having a benzophenone skeleton. In this case, when a coating film formed of the photosensitive resin composition is partially exposed to light and then developed, curing of the unexposed portion is suppressed, and thus the resolution is particularly high. Therefore, a cured product of the photosensitive resin composition having a very fine pattern can be formed. In particular, when the interlayer insulating layer 7 of the multilayer printed wiring board 20 is produced from the photosensitive resin composition and the small-diameter hole 6 for forming the through hole 10 is provided in the interlayer insulating layer 7 by photolithography (see fig. 1C and 1D), the small-diameter hole 6 can be formed precisely and easily. Examples of the photopolymerization initiator having a benzophenone skeleton include bis (diethylamino) benzophenone.

The amount of the photopolymerization initiator having a benzophenone skeleton to the acylphosphine oxide photopolymerization initiator is preferably in the range of 0.5 to 20% by mass. When the amount of the photopolymerization initiator having a benzophenone skeleton relative to the acylphosphine oxide photopolymerization initiator is 0.5% by mass or more, the resolution is particularly high. When the amount of the photopolymerization initiator having a benzophenone skeleton relative to the acylphosphine oxide photopolymerization initiator is 20% by mass or less, the photopolymerization initiator having a benzophenone skeleton hardly inhibits electrical insulation of a cured product of the photosensitive resin composition. From the same viewpoint, the amount of bis (diethylamino) benzophenone relative to the acylphosphine oxide-based photopolymerization initiator is preferably in the range of 0.5 to 20% by mass. Here, since 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 good developability cannot be obtained from the photosensitive resin composition arises. From such a viewpoint, in order to obtain a good resolution of the photosensitive resin composition, the amount of the photopolymerization initiator having a benzophenone skeleton is particularly preferably in the range of 1 to 18% by mass relative to the acylphosphine oxide-based photopolymerization initiator. From the same viewpoint, the amount of bis (diethylamino) benzophenone is particularly preferably in the range of 1 to 18% by mass relative to the acylphosphine oxide-based photopolymerization initiator.

The photopolymerization initiator (C) is not limited to the above-mentioned preferable examples, and may contain at least one component appropriately selected from known compounds.

The photosensitive resin composition may further contain a known photopolymerization accelerator, a sensitizer, and the like. For example, the photosensitive resin composition may contain a compound selected from benzoin and alkyl ethers thereof; acetophenones such as acetophenone and benzyl dimethyl ketal; anthraquinones such as 2-methylanthraquinone; thioxanthones such as 2, 4-dimethylthioxanthone, 2, 4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone and 2, 4-diisopropylthioxanthone; benzophenones such as benzophenone and 4-benzoyl-4' -methyldiphenyl sulfide; xanthones such as 2, 4-diisopropylxanthone; and α -hydroxyketones such as 2-hydroxy-2-methyl-1-phenyl-propan-1-one; at least one component selected from compounds containing nitrogen atoms such as 2-methyl-1- [ 4- (methylthio) phenyl ] -2-morpholinyl-1-propanone. The photosensitive resin composition may contain a photopolymerization initiator (C), a known photopolymerization accelerator such as a tertiary amine system including ethyl p-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, ethyl 2-dimethylaminobenzoate, and a sensitizer. The photosensitive resin composition may contain at least one of a photopolymerization initiator for visible light exposure and a photopolymerization initiator for near-infrared light exposure as necessary. The photosensitive resin composition may contain a photopolymerization initiator (C) and coumarin derivatives such as 7-diethylamino-4-methylcoumarin, carbocyanine-based compounds, xanthene-based compounds, and the like as a sensitizer for laser exposure.

The epoxy compound (D) can impart thermosetting properties to the photosensitive resin composition. The epoxy compound (D) preferably has at least 2 epoxy groups in 1 molecule. The epoxy compound (D) may be a solvent-insoluble epoxy compound or a general-purpose solvent-soluble epoxy compound. The epoxy compound (D) preferably contains a compound selected from the group consisting of phenol novolak type epoxy resins (as a specific example, product model EPICLON-775 manufactured by DIC corporation), cresol novolak type epoxy resins (as a specific example, product model EPICLON-695 manufactured by DIC corporation), bisphenol A novolak type epoxy resins (as a specific example, product model EPICLON-865 manufactured by DIC corporation), bisphenol A type epoxy resins (as a specific example, product model JeR1001 manufactured by Mitsubishi chemical corporation), bisphenol F type epoxy resins (as a specific example, product model JeR400 4004P manufactured by Mitsubishi chemical corporation), bisphenol S type epoxy resins (as a specific example, product model EPICLON EXA-1514 manufactured by DIC corporation), bisphenol AD type epoxy resins, and biphenyl type epoxy resins (as a specific example, product model EPICYX 4000 manufactured by Mitsubishi chemical corporation), A phenol novolak type epoxy resin (as a specific example, a product model NC-3000 made by Nippon chemical Co., Ltd.), a hydrogenated bisphenol A type epoxy resin (as a specific example, a product model ST-4000D made by Nippon Tekken chemical Co., Ltd.), a naphthalene type epoxy resin (as a specific example, a product model EPICLON HP-4032, EPICLON HP-4700, EPICLON HP-4770 made by Nippon Tekken chemical Co., Ltd.), a hydroquinone type epoxy resin (as a specific example, a product model EPICLON HP-1312 made by Nippon Tekken chemical Co., Ltd.), a tert-butyl catechol type epoxy resin (as a specific example, a product model EPICLON HP-820 made by Nippon chemical Co., Ltd.), a dicyclopentadiene type epoxy resin (as a specific example, a product model EPICLON HP-7200 made by ICDIC) and an adamantane type epoxy resin (as a specific example, a product model ADAMANTATE X-E-201 made by Nikken chemical Co., Ltd.), Bisphenol type epoxy resins (as a specific example, a product model YSLV-80 XY of Nippon Tekken chemical Co., Ltd.), biphenyl ether type epoxy resins (as a specific example, a product model YSLV-80 DE of Nippon Tekken chemical Co., Ltd.), tetraphenylethane type epoxy resins (as a specific example, a product model GTR-1800 of Nippon Tekken chemical Co., Ltd.), epoxy resins having a bisphenol fluorene skeleton (as a specific example, epoxy resins having a structure (S7)), a rubber-like core-shell polymer-modified bisphenol A type epoxy resin (as a specific example, product model MX-156 made by Mitsubishi chemical corporation), a rubber-like core-shell polymer-modified bisphenol F type epoxy resin (as a specific example, product model MX-136 made by Mitsubishi chemical corporation), and a special bifunctional type epoxy resin (as a specific example, product models YL 7175-500 and YL 7175-1000 made by Mitsubishi chemical corporation; product types EPICLON TSR-960, EPICLON TER-601, EPICLON TSR-250-80 BX, EPICLON 1650-75 MPX, EPICLON EXA-4850, EPICLON EXA-4816, EPICLON EXA-4822 and EPICLON EXA-9726 available from DIC corporation; YSLV-120 TE, a product of Nippon Tekko Kaisha).

The epoxy compound (D) preferably contains a crystalline epoxy resin. In this case, the developability of the photosensitive resin composition can be improved. The crystalline epoxy resin is an epoxy resin having a melting point. The crystalline epoxy resin may contain, for example, a compound selected from the group consisting of triglycidyl isocyanurate (1,3, 5-tris (2, 3-epoxypropyl) -1, 3, 5-triazine-2, 4,6(1H,3H,5H) -trione), hydroquinone-type crystalline epoxy resin (as a specific example, the product name YDC-1312 made by Nippon Tekko Kagaku K.K.), biphenyl-type crystalline epoxy resin (as a specific example, the product model YX-4000 made by Mitsubishi chemical Co., Ltd.), diphenyl ether-type crystalline epoxy resin (as a specific example, the product model YSLV-80 DE made by Nippon Tekko Kagaku K.K.), bisphenol-type crystalline epoxy resin (as a specific example, the product model YSLV-80 XY made by Nippon Tekko Kagaku K.K.), and tetraphenolethane-type crystalline epoxy resin (as a specific example, the product model GTR-1800 made by Nippon Kagaku K.K.), At least one component of bisphenol fluorene type crystalline epoxy resin (specifically, epoxy resin having a structure (S7)).

The amount of the crystalline epoxy resin relative to the epoxy compound (D) is preferably within a range of 10 to 100% by mass, more preferably within a range of 30 to 100% by mass, and still more preferably within a range of 35 to 100% by mass. In this case, the thermosetting reaction of the carboxyl group-containing resin and the epoxy resin is suppressed in the step before the photosensitive resin composition is thermally cured, and the developability can be improved.

The crystalline epoxy resin is particularly preferably one having a melting point of 110 ℃ or lower. That is, the epoxy compound (D) preferably 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, for example, at least one component selected from the group consisting of a biphenyl-type epoxy resin (specifically, a product model YX4000 manufactured by Mitsubishi chemical corporation), a biphenyl ether-type epoxy resin (specifically, a product model YSLV-80 DE manufactured by Nippon Tekko chemical Co., Ltd.) and a bisphenol-type epoxy resin (specifically, a product model YSLV-80 XY manufactured by Nippon Tekko chemical Co., Ltd.).

The epoxy compound (D) may contain triglycidyl isocyanurate. The triglycidyl isocyanurate is particularly preferably a β -isomer having a structure in which 3 epoxy groups are bonded to the S-triazine ring skeleton surface in the same direction, or a mixture of the β -isomer and an α -isomer having a structure in which 1 epoxy group and 2 other epoxy groups are bonded to the S-triazine ring skeleton surface in different directions.

The crystalline epoxy resin also preferably contains a crystalline epoxy resin having a melting point of less than 100 ℃. That is, the epoxy compound (D) preferably further contains a crystalline epoxy resin having a melting point of less than 100 ℃. In this case, the developability of the photosensitive resin composition can be further improved. Further, since the crystalline epoxy resin having a melting point of less than 100 ℃ has high compatibility with components other than the epoxy resin (D) in the photosensitive resin composition, a solvent, and the like, it is easily dispersed in the photosensitive resin composition and homogenized. Further, when the photosensitive resin composition contains a crystalline epoxy resin having a melting point of less than 100 ℃, crystallization is less likely to occur even at low temperatures. Therefore, the photosensitive resin composition can be provided with high storage stability. In addition, since the crosslinking reaction of the carboxyl group and the epoxy group in the photosensitive resin composition is suppressed at low temperature, it is possible to maintain good developability of the photosensitive resin composition and to impart high storage stability to the photosensitive resin composition.

The crystalline epoxy resin having a melting point of less than 100 ℃ may contain, for example, at least one component selected from the group consisting of a biphenyl ether type epoxy resin (as a specific example, YSLV-80 DE, a product of Nippon Tekken chemical Co., Ltd.), a bisphenol type epoxy resin (as a specific example, YSLV-80 XY, a product of Nippon Tekken chemical Co., Ltd.), and an epoxy resin having a bisphenol fluorene skeleton (as a specific example, an epoxy resin having the structure (S7)).

When the epoxy compound (D) contains a crystalline epoxy resin having a melting point of less than 100 ℃, the equivalent of the epoxy group contained in the crystalline epoxy resin having a melting point of less than 100 ℃ is preferably in the range of 0.2 to 2.0, more preferably in the range of 0.25 to 1.7, and still more preferably in the range of 0.3 to 1.5 relative to 1 equivalent of the carboxyl group contained in the carboxyl group-containing resin (A).

The epoxy compound (D) may contain a phosphorus-containing epoxy resin. In this case, the cured product of the photosensitive resin composition has improved flame retardancy. Examples of the phosphorus-containing epoxy resin include phosphoric acid-modified bisphenol F type epoxy resins (specific examples thereof include EPICLON EXA-9726 and EPICLON EXA-9710 available from DIC corporation) and Epotohto FX-305 available from Nippon Ciscos.

The photosensitive resin composition preferably further contains an organic filler (E). In this case, the adhesion between the interlayer insulating layer 7 and the conductor layer 8 is further improved. The organic filler (E) can also improve the thixotropy of the photosensitive resin composition, thereby improving the stability (particularly, the storage stability).

The organic filler (E) preferably has a polar group. In this case, the adhesion between the interlayer insulating layer 7 and the conductor layer 8 is particularly improved. The polar group particularly preferably contains at least one group selected from a carboxyl group, an amino group and a hydroxyl group. In this case, the adhesion is particularly improved.

When the polar group particularly includes a carboxyl group, the developability of a cured product of the photosensitive resin composition can be improved, and when the photosensitive resin composition includes a crystalline epoxy compound, the solubility of the crystalline epoxy compound in the photosensitive resin composition can be improved to prevent crystallization.

When the polar group particularly includes a hydroxyl group, the dispersibility of the organic filler (E) in the photosensitive resin composition is improved.

When the polar group particularly includes an amino group, the reactivity of the carboxyl group-containing resin (a) with the epoxy compound (D) can be improved, and thus the acid resistance and alkali resistance of the cured film can be improved.

When the polar group of the organic filler (E) contains a carboxyl group, the acid value of the organic filler (E) is preferably in the range of 1mgKOH/g to 60 mgKOH/g. When 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. When the acid value is more than 60mgKOH/g, the moisture resistance reliability of the cured product may be lowered. The acid value of the organic filler (E) is more preferably 3mgKOH/g or more, and still more preferably 40mgKOH/g or less.

When the polar group includes a carboxyl group, the organic filler (E) is obtained by polymerizing or crosslinking a carboxylic acid monomer having a polymerizable unsaturated double bond, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid.

The organic filler (E) may be blended in the photosensitive resin composition in the form of a dispersion, for example, but is not limited thereto.

The organic filler (E) preferably contains a rubber component having a polar group. In this case, the polar group contains, for example, a carboxyl group, or contains a carboxyl group and a hydroxyl group. 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 photosensitive resin composition can have high transparency, and the resolution can be improved. In addition, the rubber component can effectively impart flexibility to the cured product of the photosensitive resin composition. NBR is a copolymer of butadiene and acrylonitrile, classified as nitrile rubber. MBS is a copolymer composed of 3 components of methyl methacrylate, butadiene, and styrene, and is classified as a butadiene rubber. SBR is a copolymer of styrene and butadiene, classified as a styrene rubber.

Specific examples of the organic filler (E) provided in the form of a dispersion include a product model XER-91-MEK (a methyl ethyl ketone dispersion having a concentration of 15% by weight of a crosslinked rubber (NBR) having a carboxyl group and an average primary particle diameter of 0.07 μm, an acid value of 10.0mgKOH/g) manufactured by JSR, product models XER-32 and XER-92 manufactured by JSR, and a product model XSK-500 (a dispersion of a crosslinked rubber (SBR) having a carboxyl group and a hydroxyl group) manufactured by JSR.

The organic filler (E) may contain components other than the rubber component. The component other than the rubber component may contain at least 1 component selected from acrylic resin particles having a carboxyl group and cellulose particles having a carboxyl group. The acrylic resin fine particles having a carboxyl group may contain at least 1 component selected from the group consisting of non-crosslinked styrene-acrylic resin fine particles and crosslinked styrene-acrylic resin fine particles. Specific examples of the non-crosslinked styrene-acrylic resin fine particles include product model FS-201 (average primary particle diameter 0.5 μm) manufactured by Nippon paint Industrial Coatings. Specific examples of the crosslinked styrene-acrylic resin fine particles include product model MG-351 (average primary particle diameter 1.0 μm) and product model BGK-001 (average primary particle diameter 1.0 μm) manufactured by Nipponpaint Industrial Coatings.

When the polar group includes an amino group, the organic filler (E) contains at least one component selected from triazine derivatives such as melamine, dicyandiamide, imidazole-based compounds, acetoguanamine, benzoguanamine, melamine-phenol-formaldehyde resins, triazine compounds, ethyldiamino-S-triazine, 2, 4-diamino-6-xylyl-S-triazine, thiazole-based compounds, and triazole-based compounds. When the polar group includes an amino group, the organic filler (E) preferably contains melamine particles. When the organic filler (E) contains melamine particles, the adhesion between the interlayer insulating layer 7 and the conductor layer 8 is particularly improved.

The organic filler (E) may contain at least one component selected from the above-described components. The organic filler (E) may contain a component having a polar group other than the above-described components.

The average primary particle diameter of the organic filler (E) is preferably 1 μm or less. In this case, the thixotropy of the photosensitive resin composition is effectively improved. Therefore, the stability of the photosensitive resin composition is further improved. The organic filler (E) has an average primary particle diameter of, for example, 0.001 μm or more. The average primary particle diameter of the organic filler (E) is a median particle diameter (D50) measured by a laser diffraction particle size distribution measuring apparatus. The average primary particle diameter of the organic filler (E) is preferably 0.1 μm or less. In this case, the stability of the photosensitive resin composition is further improved, and the resolution is further improved because scattering at the time of exposure is suppressed.

The particle diameter of the organic filler (E) in the photosensitive resin composition is preferably 10 μm or less. The organic filler (E) may contain secondary particles formed by aggregation in the photosensitive resin composition. In this case, the particle diameter of the organic filler (E) in the photosensitive resin composition means the particle diameter of the particles including the secondary particles. The particle diameter of the organic filler (E) in the photosensitive resin composition can be measured using a laser diffraction scattering particle size distribution measuring apparatus or an optical microscope. When the particle size of the organic filler (E) in the photosensitive resin composition is 10 μm or less, the organic filler (E) can be well dispersed in the photosensitive resin composition and the interlayer insulating layer 7, and thus the adhesion between the interlayer insulating layer 7 and the conductor layer 8 is particularly improved. In addition, the stability of the photosensitive resin composition is further improved, and the resolution is further improved because scattering at the time of exposure is suppressed. The particle diameter of the organic filler (E) in the photosensitive resin composition is more preferably 5 μm or less, still more preferably 1 μm or less, and particularly preferably 0.5 μm or less. The particle size is, for example, 0.01 μm or more.

The photosensitive resin composition may contain an organic solvent. The organic solvent is used for the purpose of liquefaction or varnish formation of the photosensitive resin composition, adjustment of viscosity, adjustment of coatability, adjustment of film forming property, and the like.

The organic solvent may contain, for example, a straight-chain, branched, secondary alcohol or polyhydric alcohol 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 SWASOLVE series (manufactured by PELLE PETROL CORPORATION), SOLVESO series (manufactured by ExxonMobil 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 at least one compound of dialkyl glycol ethers.

The amounts of the components in the photosensitive resin composition are appropriately adjusted so that the photosensitive resin composition has photocurability and can be developed with an alkaline solution.

The amount of the carboxyl group-containing resin (a) relative to the amount of the solid component of the photosensitive resin composition is preferably within a range of 5 to 85 mass%, more preferably within a range of 10 to 75 mass%, and still more preferably within a range of 30 to 60 mass%. The amount of the carboxyl group-containing resin (a1) relative to the amount of the solid component of the photosensitive resin composition is preferably within a range of 5 to 85 mass%, more preferably within a range of 10 to 75 mass%, and still more preferably within a range of 30 to 60 mass%.

The amount of the unsaturated compound (B) to the carboxyl group-containing resin (A) is preferably in the range of 1 to 50% by mass, more preferably in the range of 10 to 45% by mass, and still more preferably in the range of 21 to 40% by mass.

The amount of the photopolymerization initiator (C) to the carboxyl group-containing resin (a) is preferably in the range of 0.1 to 30% by mass, and more preferably in the range of 1 to 25% by mass.

The total amount of the epoxy groups contained in the epoxy compounds (D) is preferably in the range of 0.7 to 2.5, more preferably 0.7 to 2.3, and still more preferably 0.7 to 2.0, based on 1 equivalent of the carboxyl groups contained in the carboxyl group-containing resin (A). The total equivalent of epoxy groups contained in the crystalline epoxy resin is preferably in the range of 0.1 to 2.0, more preferably in the range of 0.2 to 1.9, and still more preferably in the range of 0.3 to 1.5 relative to 1 equivalent of carboxyl groups contained in the carboxyl group-containing resin (a). Alternatively, the total of the equivalents of epoxy groups contained in the crystalline epoxy resin may be in the range of 0.7 to 2.5 relative to 1 equivalent of carboxyl groups contained in the carboxyl group-containing resin (a).

The amount of the organic filler (E) is preferably in the range of 1 to 50 parts by mass per 100 parts by mass of the carboxyl group-containing resin (a). By setting the amount of the organic filler (E) to 1 part by mass or more, the adhesion between the interlayer insulating layer 7 and the conductor layer 8 is particularly high, and good copper plating adhesion of a cured product of the photosensitive resin composition can be obtained. In addition, when the amount of the organic filler (E) is 50 parts by mass or less, excellent resolution of the photosensitive resin composition can be obtained. When the content of the organic filler (E) is in the above range, the thixotropy of the photosensitive resin composition is improved and the stability is improved. The amount of the organic filler (E) is more preferably 5 parts by mass or more, and still more preferably 10 parts by mass or more. In addition, the amount of the organic filler (E) is more preferably 30 parts by mass or less, and still more preferably 20 parts by mass or less.

When the photosensitive resin composition contains an organic solvent, the amount of the organic solvent is preferably adjusted so that the organic solvent rapidly volatilizes and disappears when a coating film formed from the photosensitive resin composition is dried, that is, so that the organic solvent does not remain in the dried film. In particular, the amount of the organic solvent is preferably in the range of 0 to 99.5% by mass, and more preferably in the range of 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 solid content is the total amount of all components obtained by removing volatile components such as a solvent from the photosensitive resin composition.

The photosensitive resin 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 an inorganic filler. In this case, the curing shrinkage of the film formed from the photosensitive resin composition is reduced. The inorganic filler may contain, for example, one or more materials selected from barium sulfate, crystalline silica, nano silica, carbon nanotubes, talc, bentonite, hydrotalcite, aluminum hydroxide, magnesium hydroxide, and titanium oxide. When the inorganic filler contains a white material such as titanium oxide or zinc oxide, the photosensitive resin composition and the cured product thereof can be whitened by the white material. When the photosensitive resin composition contains an inorganic filler, the amount of the inorganic filler relative to the carboxyl group-containing resin (a) is preferably in the range of more than 0 mass% and 300 mass% or less.

The photosensitive resin composition may contain a blocked isocyanate selected from the group consisting of tolylene diisocyanate blocked with caprolactam, oxime, malonate, etc., morpholine diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate; amino resins such as melamine resin, n-butylated melamine resin, isobutylated melamine resin, butylated urea resin, butylated melamine urea co-condensation resin, and benzoguanamine co-condensation resin; various thermosetting resins other than the 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 resin, phenoxy resin, polyurethane resin, fluorine resin, and other polymer 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, 2 MZ-A, 2 MZ-OK, 2PHZ, 2P4BHZ, 2P4MHZ (both trade names of imidazole compounds), U-CAT 3503N manufactured by San-Apro corporation, U-CAT 3502T (both trade names of blocked isocyanate compounds of dimethylamine), DBU, DBN, U-CATA SA102, and U-CAT 5002 (both bicyclic amidine compounds and salts thereof).

The photosensitive resin composition may contain an adhesion-imparting agent. Examples of the adhesion-imparting agent include S-triazine derivatives such as guanamine, acetoguanamine, benzoguanamine, and 2, 4-diamino-6-methacryloyloxyethyl-S-triazine, 2-vinyl-4, 6-diamino-S-triazine/isocyanuric acid adduct, and 2, 4-diamino-6-methacryloyloxyethyl-S-triazine/isocyanuric acid adduct.

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, products of BYK Japan K.K.), polyhydroxycarboxylic acid amides (BYK-405, products of BYK Japan K.K.), modified ureas (BYK-410, BYK-411 and BYK-420, products of BYK Japan K.K.), high molecular urea derivatives (BYK-415, products of BYK Japan K.K.), urea-modified polyurethanes (BYK-425, products of BYK Japan K.K.K.K.K.K.K.), polyurethanes (BYK-428, products of BYK Japan K.K.K.), castor oil waxes, polyethylene waxes, polyamide waxes, bentonites, silica gels, kaolins, and clays.

The photosensitive resin composition may contain a curing accelerator; a colorant; copolymers such as silicone and acrylic ester; leveling agent; adhesion imparting agents such as silane coupling agents; a thixotropic agent; a polymerization inhibitor; an antihalation agent; a flame retardant; defoaming agents; an antioxidant; a surfactant; and at least one component of a polymeric dispersant.

The photosensitive resin composition is, for example, in a liquid state. When the photosensitive resin composition is in a liquid state, for example, the above-described raw materials of the photosensitive resin composition are mixed and kneaded by a known kneading method using, for example, a three-roll mill, a ball mill, a sand mill, or the like, thereby preparing the photosensitive resin composition. When the photosensitive resin composition contains a liquid component, a component having a low viscosity, or the like in the raw material, a portion other than the liquid component, the component having a low viscosity, or the like in the raw material may be first kneaded, and 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. For example, when any of the raw materials is dispersed in a solvent, the photosensitive resin composition can be prepared by mixing and stirring the raw materials without kneading.

In consideration of storage stability and the like, a part of the components of the photosensitive resin composition may be mixed to prepare a first dose, and the remaining components may be mixed to prepare a second dose. That is, the photosensitive resin composition may have a first component and a second component. In this case, for example, the unsaturated compound (B), a part of the organic solvent, and the thermosetting component in the components of the photosensitive resin composition may be mixed and dispersed in advance to prepare a first dose, and the remaining part of the components of the photosensitive resin composition may be mixed and dispersed to prepare a second dose. In this case, a mixed solution is prepared by mixing the first agent and the second agent in required amounts at appropriate times, and the mixed solution is solidified to obtain a solidified substance.

The photosensitive resin composition may be a dry film. The dry film can be produced by, for example, applying a liquid composition similar to the liquid photosensitive resin composition described above onto an appropriate support made of polyester or the like, and then drying the composition. In this way, a laminate (dry film with a support) including the dry film and a support for supporting the dry film is obtained.

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 sodium carbonate solution. In this case, the interlayer insulating layer 7 having a sufficient thickness can be formed from the photosensitive resin composition by photolithography. Of course, the interlayer insulating layer 7 having a thickness of less than 25 μm can be produced from the photosensitive resin composition.

Whether or not the coating film 4 having a thickness of 25 μm can be developed with an aqueous sodium carbonate solution can be confirmed by the following method. A photosensitive resin composition is applied to an appropriate substrate to form a wet coating film, 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 a transmission part for transmitting ultraviolet rays and a shielding part for shielding ultraviolet rays is directly contacted with the coating film 4 at a rate of 500mJ/cm²The coating 4 is exposed to ultraviolet light. After exposure, the treatments were as follows: spraying 1% Na at 30 deg.C under 0.2MPa₂CO₃The aqueous solution was sprayed to the coating film 4 for 90 seconds, and then pure water was sprayed at a spray pressure of 0.2MPa for 90 seconds. After this treatment, the coating film 4 was observed, and as a result, when the portion of the coating film 4 corresponding to the shielding portion was removed and no residue was observed, it was judged that the coating film 4 having a thickness of 25 μm could be developed with an aqueous sodium carbonate solution.

An example of a method for manufacturing a multilayer printed wiring board 20 including an interlayer insulating layer 7 made of a photosensitive resin composition will be described below with reference to fig. 1A to 1E.

In the method, a photosensitive resin composition is disposed on the printed wiring board 1, and the photosensitive resin composition is photocured to produce the cured film 11. Next, the cured film 11 is treated with an alkaline solution, and then the conductor layer 8 in contact with the cured film 11 is formed.

Specifically, first, as shown in fig. 1A, the printed wiring board 1 is prepared. The printed wiring board 1 includes at least, for example, an insulating layer 2 and a conductor wiring 3 located thereon.

As shown in fig. 1B, a coating film 4 is produced by disposing a photosensitive resin composition on the printed wiring board 1 so as to cover the conductor wiring 3.

When the photosensitive resin composition is in a liquid state, the photosensitive resin composition is applied to, for example, the printed wiring board 1 to form a wet coating film in the production of the coating film 4. The method of applying the photosensitive resin composition is a known method, and examples thereof include a dipping method, a spray method, a spin coating method, a roll coating method, a curtain coating method, and a screen printing method. Next, the wet coating film is dried at a temperature in the range of, for example, 60 to 120 ℃ in order to volatilize the organic solvent in the photosensitive resin composition. This enables the film 4 to be produced.

When the photosensitive resin composition is a dry film, the film 4 is formed by, for example, superimposing the dry film on the printed wiring board 1 in a state of being supported by a support. In this state, pressure is applied to the dry film and the printed wiring board 1, and then the support is peeled off from the dry film, thereby transferring the dry film from the support onto the printed wiring board 1. Thus, the film 4 made of a dry film is provided on the printed wiring board 1.

Then, the coating film 4 is photocured to produce a cured film 11. For this purpose, the coating 4 is partially cured as shown in fig. 1C, for example, by exposing the coating 4 to light. Therefore, for example, after the negative mask is brought into contact with the film 4, the film 4 is irradiated with ultraviolet rays. The negative mask includes a transmission portion for transmitting ultraviolet rays and a shielding portion for shielding ultraviolet rays, and the shielding portion is provided at a position corresponding to the position of the through hole 10. The negative mask is an optical device such as a mask film or a dry plate. The light source of ultraviolet rays may be 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, metal halide lamps, LEDs, g-lines (436nm), h-lines (405nm), i-lines (365nm), and combinations of two or more of the g-lines, h-lines, and i-lines.

The exposure method may be a method other than the method using a negative mask. For example, the film 4 may be exposed by a direct drawing 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 used for the direct writing method may be selected from, for example, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, an LED, a g-line (436nm), an h-line (405nm), an i-line (365nm), and a combination of two or more of the g-line, the h-line, and the i-line.

In the case where the photosensitive resin composition is a dry film, the dry film in the laminate may be superposed on the printed wiring board 1, and then the film 4 may be exposed by irradiating ultraviolet rays through the support to the film 4 made of the dry film without peeling the support, and then the support and the film 4 may be peeled off before the development treatment.

In the case where the multilayer printed wiring board 20 is not provided with the through-hole 10, for example, the cured film 11 may be produced by photocuring the entire coating 4, instead of partially photocuring the coating 4.

Next, the cured film 11 is treated with an alkaline solution. When the cured film 11 is subjected to heat treatment before the conductor layer 8 is formed, the cured film 11 is preferably treated with an alkaline solution before the heat treatment.

The alkaline solution is, for example, an alkaline aqueous solution containing either or both of an alkali metal salt and an alkali metal hydroxide. More specifically, the basic aqueous solution contains at least one member selected from, for example, 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 pH value of the alkaline solution is preferably 8.5-14. The pH of the alkaline solution is more preferably 9 or more, still more preferably 9.5 or more, and particularly preferably 10 or more. The pH of the alkali solution is more preferably 13.5 or less, still more preferably 13 or less, and particularly preferably 12.5 or less.

When the coating 4 is partially photocured, the unexposed portion 5 of the coating 4 can be removed from the printed wiring board 1 by an alkaline solution while treating the cured film 11 with the alkaline solution. That is, the cured film 11 may be treated with an alkaline solution while being subjected to a development treatment with the alkaline solution. Thus, as shown in fig. 1D, the hole 6 may be provided at a position where the through-hole 10 is formed.

The treatment with the alkaline solution is preferably performed in a state where the reaction rate of the epoxy group based on the film 4 is 50% or less. The reaction rate of the epoxy groups is based on the amount of epoxy groups in the film 4 before exposure. The treatment with the alkaline solution is more preferably performed in a state where the reaction rate of the epoxy group is 40% or less, and still more preferably performed in a state where the reaction rate of the epoxy group is 40% or lessThe reaction is carried out in a state of 30% or less, and particularly preferably in a state of 20% or less. The reaction rate of epoxy groups was 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the coating film 4 and the cured film 11^-1The intensity of the peak derived from the epoxy group (c) was calculated. Specifically, the reaction rate of the epoxy group was determined from 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the coating film 4^-1Normalized value (S) of the area of the peak of (1)₀) And 910cm in IR spectrum obtained in infrared spectroscopic analysis of cured film 11 after treatment with alkaline solution^-1Normalized value (S) of the area of the peak of (1)₁) And according to (S)₀－S₁)÷S₀X 100 (%). The normalized value (S) is₀) And normalized value (S)₁) The value of (A) is a peak in the IR spectrum which does not change even when the film 4 is exposed to light, for example, 750cm^-1The area of the peak of (a) is a relative value of the reference. I.e. the normalized value (S)₀) 910cm in the IR spectrum obtained by the infrared spectroscopic analysis of film 4^-1Measured value of the area of the peak (P)₀) And 750cm^-1Measured value of the area of the peak (R)₀) Presence of S₀＝P₀/R₀The relationship (2) of (c). In addition, the value (S) is normalized₁) 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the cured film 11^-1Measured value of the area of the peak (P)₁) And 750cm^-1Measured value of the area of the peak (R)₁) Presence of S₁＝P₁/R₁The relationship (2) of (c).

The cured film 11 may be cleaned with a known chemical solution after the treatment with the alkaline solution and before the conductor layer 8 is formed. The cleaning treatment is preferably a treatment that does not roughen the cured film 11. In the washing treatment, for example, the cleaning solution (containing 40ml/L Atotech Japan company, make the Cleaner securiganteh 902, 3ml/L Cleaner added 902, concentration 20g/L NaOH liquid) to the cured product 11 cleaning. Next, the cured film 11 was immersed in an aqueous solution containing sodium persulfate at a concentration of 100g/L and sulfuric acid at a concentration of 10ml/L, and then water washing was continued.

Next, the conductor layer 8 is formed in contact with the cured film 11. The conductor layer 8 is a conductor wiring made of metal such as copper, for example. As described above, the arithmetic mean roughness Ra specified in JIS B0601-2001 of the surface of the cured film 11 in contact with the conductor layer 8 immediately before the conductor layer 8 is formed is less than 150 nm. This can be easily achieved by forming the cured film 11 from the photosensitive resin composition by a general method, for example, the method described above.

When the arithmetic average roughness Ra is less than 150nm, the multilayer printed wiring board 20 can have good high-frequency characteristics. The arithmetic average roughness Ra is preferably less than 100nm, more preferably less than 80nm, and particularly preferably less than 30 nm. The arithmetic average roughness Ra is, for example, 5nm or more.

In the case where the hole 6 is formed in the cured film 11, the through-hole 10 is made by forming the hole plating layer 9 inside the hole 6. In fig. 1E, the hole plating layer 9 has a cylindrical shape covering the inner surface of the hole 6, but the hole plating layer 9 may be filled inside the entire hole 6.

The conductor layer 8 and the via plating layer 9 can be formed by a known method such as an Additive method.

After the conductor layer 8 is formed, the cured film 11 is preferably subjected to heat treatment. In this case, the adhesion between the interlayer insulating layer 7 made of the cured film 11 and the conductor layer 8 can be further improved. The conditions of the heat treatment are, for example, a heating temperature in the range of 120 to 200 ℃ and a heating time in the range of 30 to 120 minutes.

The conductor layer 8 may also be produced by subjecting the cured film 11 to electroless plating treatment and electroplating treatment in this order. In this case, it is preferable to perform the heating process between the electroless plating process and the plating process, and further perform the heating process after the plating process. In this case, the adhesion between the interlayer insulating layer 7 made of the cured film 11 and the conductor layer 8 can be further improved.

It is preferable that the cured film 11 is not subjected to the heat treatment or the heat treatment is performed so as to satisfy either or both of the heating temperature of 200 ℃ or less and the heating time of 150 minutes or less during the period from the production of the cured film 11 to the production of the conductor layer 8. That is, it is preferable that the cured film 11 is not subjected to the heat treatment during the period from the production of the cured film 11 to the production of the conductor layer 8, and even when the heat treatment is performed, it is preferable that either or both of the heating temperature is 200 ℃ or less and the heating time is 150 minutes or less be satisfied. The heating temperature is more preferably 180 ℃ or lower, still more preferably 160 ℃ or lower, and particularly preferably 140 ℃ or lower. The heating time is more preferably 120 minutes or less, still more preferably 90 minutes or less, and particularly preferably 60 minutes or less.

The heat treatment is preferably performed until the reaction rate of epoxy groups based on the coating film 4 in the cured film 11 after the heat treatment is less than 95%. The reaction rate of the epoxy groups is based on the amount of epoxy groups in the film 4 before exposure. The heat treatment is more preferably carried out until the reaction rate of the epoxy group becomes less than 90%, further preferably less than 85%, particularly preferably less than 80%. The reaction rate of epoxy groups was 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the coating film 4 and the cured film 11 after heat treatment^-1The intensity of the peak derived from the epoxy group (c) was calculated. Specifically, the reaction rate of the epoxy group was determined from 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the coating film 4^-1Normalized value (S) of the area of the peak of (1)₀) And 910cm in IR spectrum obtained in infrared spectroscopic analysis of the cured film 11 after the heat treatment^-1Normalized value (S) of the area of the peak of (1)₂) And according to (S)₀－S₂)÷S₀X 100 (%). The normalized value (S) is₀) And normalized value (S)₂) The value of (A) is a peak in the IR spectrum which does not change even when the film 4 is exposed to light, for example, 750cm^-1The area of the peak of (a) is a relative value of the reference. I.e. the normalized value (S)₀) 910cm in the IR spectrum obtained by the infrared spectroscopic analysis of film 4^-1Measured value of the area of the peak (P)₀) And 750cm^-1Measured value of the area of the peak (R)₀) Presence of S₀＝P₀/R₀The relationship (2) of (c). In addition, the value (S) is normalized₂) 910cm in the IR spectrum obtained by infrared spectroscopic analysis of the cured film 11^-1Measured value of the area of the peak (P)₂) And 750cm^-1Measured value of the area of the peak (R)₂) Presence of S₂＝P₂/R₂The relationship (2) of (c).

In this case, the adhesion between the interlayer insulating layer 7 and the conductor layer 8 can be particularly improved. The reason is not sufficiently clear, but is presumed as follows: if the conditions are within the above ranges without heat treatment or even with heat treatment, a larger amount of functional groups derived from components in the photosensitive resin composition are present on the surface of the cured film 11 than would otherwise be the case, and the interaction between the functional groups and the conductor layer 8 contributes to the improvement in adhesion.

It is preferable that the treatment with the oxidizing agent is not performed on the cured film 11 during the period from the production of the cured film 11 to the production of the conductor layer 8. In this case, the roughness of the cured film 11 due to the oxidizing agent is prevented, and the arithmetic average roughness Ra of the cured film 11 is easily made smaller than 150 nm. Even when the treatment is performed based on an oxidizing agent, the above-described treatment is preferably performed so that the arithmetic average roughness Ra of the cured film 11 is less than 150 nm.

When the holes 6 are provided in the cured film 11, desmear treatment using an oxidizing agent is performed on the cured film 11 before the conductor layer 8 is formed, which is useful for removing desmear in the holes 6. However, in the present embodiment, since the photosensitive resin composition can have excellent developability and resolution, the smear is not likely to remain even if the hole 6 is provided in the cured film 11. Therefore, even if the treatment with the oxidizing agent is not performed or even if the treatment with the oxidizing agent is performed slightly, the trouble due to the skim is less likely to occur.

As described above, the multilayer printed wiring board 20 including the interlayer insulating layer 7 formed of the cured film 11 and the conductor layer 8 in contact with the interlayer insulating layer 7 can be manufactured. The thickness of the interlayer insulating layer 7 is, for example, in the range of 3 to 50 μm. As described above, in the multilayer printed wiring board 20, even if the interlayer insulating layer 7 is not roughened or the degree of roughening is small, high adhesion between the interlayer insulating layer 7 and the conductor layer 8 can be achieved.

Examples

Hereinafter, specific examples of the present invention will be described. The present invention is not limited to the following examples.

[ examples, comparative examples and reference examples ]

(1) Synthesis of carboxyl group-containing resin

[ Synthesis example A-1 ]

Into a four-necked flask equipped with a reflux condenser, a thermometer, an air blowing tube and a stirrer, R in the formula (2) and represented by the formula (2)¹～R⁷A mixture was prepared of 250 parts by mass of a bisphenol fluorene type epoxy resin (epoxy equivalent 250g/eq) containing all hydrogen, 60 parts by mass of propylene glycol monomethyl ether acetate, 140 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 part by mass of methylhydroquinone, 72 parts by mass of acrylic acid, and 1.5 parts by mass of triphenylphosphine. The mixture was heated at 115 ℃ for 12 hours in a flask while stirring with bubbling of air. Thus, a solution of the intermediate was prepared.

Next, 58.8 parts by mass of 3,3 ', 4, 4' -biphenyltetracarboxylic dianhydride, 60.8 parts by mass of tetrahydrophthalic anhydride, and 38.7 parts by mass of propylene glycol monomethyl ether acetate were added to the solution of the intermediate in the flask, and the solution was heated at 115 ℃ for 6 hours and further at 80 ℃ for 1 hour while stirring with bubbling of air. Thus, a 65 mass% solution of the carboxyl group-containing resin A-1 was obtained. The weight-average molecular weight of the carboxyl group-containing resin A-1 was 3096, and the acid value was 105 mgKOH/g.

[ Synthesis example A-2 ]

The carboxyl group-containing resin having an aromatic ring of Synthesis example A-2 was prepared as follows. 288 parts by mass of a biphenyl novolak type epoxy resin (product model NC-3000-H, epoxy equivalent 288g/eq, manufactured by Nippon chemical Co., Ltd.), 155 parts by mass of diethylene glycol monoethyl ether acetate, 0.2 part by mass of methylhydroquinone, 72 parts by mass of acrylic acid and 3 parts by mass of triphenylphosphine were charged into 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 115 ℃ for 12 hours in a flask while stirring with bubbling air. Thus, a solution of the intermediate was prepared.

Then, 91.2 parts by mass of tetrahydrophthalic anhydride and 90 parts by mass of diethylene glycol monoethyl ether acetate were added to 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 mass% solution of the carboxyl group-containing resin A-2 was obtained. The weight average molecular weight of the carboxyl group-containing resin A-2 was 8120, and the acid value was 76 mgKOH/g.

(2) Preparation of photosensitive resin composition (composition examples 1 to 9)

The components shown in Table 1 were mixed in a flask, and stirred and mixed at a temperature of 35 ℃ for 2 hours to obtain photosensitive resin compositions of composition examples 1 to 9 (see the tables). The photosensitive resin compositions of composition examples 1 to 9 were filtered through a 300-mesh filter, and then further filtered through a filter having a pore size of 10 μm. The particle diameters of the organic fillers contained in the photosensitive resin compositions of composition examples 1 to 9 were confirmed by a laser diffraction scattering particle size distribution measuring apparatus, and as a result, the maximum particle diameters were all 10 μm or less.

The blending amount in table 1 represents the mass part of the solid content of the components shown in the table. Although not shown in the table, methyl ethyl ketone was added as a diluent to the photosensitive resin composition.

The details of the components shown in table 1 are as follows.

Organic filler a having polar groups (dispersion liquid): a methyl ethyl ketone dispersion containing 15 wt% of a crosslinked rubber (NBR) having a carboxyl group and an average primary particle diameter of 0.07 μm, model No. XER-91-MEK manufactured by JSR, and having an acid value of 10.0 mgKOH/g.

Organic filler B having polar group (dispersion liquid): a methyl ethyl ketone dispersion containing a crosslinked rubber (SBR) having a carboxyl group and a hydroxyl group and having an average primary particle diameter of 0.07 μm at a concentration of 15% by weight, model XSK-500 manufactured by JSR Corp.

Organic filler C having polar group (dispersion liquid): manufactured by Nissan chemical industries, Ltd. A fine melamine powder dispersed varnish was prepared by dispersing 1.5 parts by mass of fine melamine powder in 3.5 parts by mass of tricyclodecane dimethanol diacrylate using a bead mill. The maximum particle size of the fine melamine powder is 5 μm or less.

Organic fillers (dispersions) having no polar groups: a glycidyl group-modified acrylonitrile butadiene rubber dispersion varnish was prepared by dispersing 1.5 parts by mass of a glycidyl group-modified acrylonitrile butadiene rubber having a powder shape and an average primary particle diameter of 0.3 μm in 2.5 parts by mass of tricyclodecane dimethanol diacrylate using a bead mill.

Coupling agent: 3-glycidoxypropyltrimethoxysilane.

Silica: the product model MEK-EC-2130Y manufactured by Nissan chemical industries, and methyl ethyl ketone dispersed silica sol, the level of compatibility with epoxy resin is improved, the solid content concentration is 30 mass%, and the average primary particle size is 10 nm-15 nm.

Unsaturated compound a: tricyclodecane dimethanol diacrylate (comprising tricyclodecane dimethanol diacrylate derived from a dispersion of organic filler).

Unsaturated compound B: trimethylolpropane triacrylate.

Unsaturated compound C: a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate, manufactured by nippon chemical co., ltd.a., product number KAYARAD DPHA.

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

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

Photopolymerization initiator C: 4, 4' -bis (diethylamino) benzophenone.

An epoxy compound: biphenyl type crystalline epoxy resin, product model YX4000, epoxy equivalent 186g/eq, Mitsubishi chemical corporation.

Antioxidant: hindered phenol antioxidant, model IRGANOX 1010 from BASF.

Surface conditioner: product number MEGAFAC F-477 manufactured by DIC corporation.

[ Table 1]

(3) Preparation of test pieces (examples 1 to 29, comparative examples 1 to 27, and reference examples 1 to 18)

Using the photosensitive resin compositions of composition examples 1 to 9, test pieces were prepared as follows. The summary of each example, comparative example and reference example is shown in tables 2 to 10.

(3-1) preparation of cured film

The photosensitive resin compositions of composition examples 1 to 9 were applied to a film made of polyethylene terephthalate by an applicator, and then dried by heating at 95 ℃ for 25 minutes to form a dry film having a thickness of 30 μm on the film.

A glass epoxy copper-clad laminate (FR-4 type) having a copper foil with a thickness of 17.5 μm was prepared. A comb-shaped electrode having a line width/pitch of 50 μm/50 μm was formed as a conductor wiring on the glass epoxy copper-clad laminate by a subtractive method (copper plating), thereby obtaining a printed wiring board.

The surface layer portion of the conductor wiring of the printed wiring board having a thickness of about 1 μm is removed by dissolving with an etchant (organic acid based microetching agent manufactured by MEC corporation, product model CZ-8101), thereby roughening the conductor wiring.

The dry film heat is laminated to the entire side of the printed wiring board using a vacuum laminator. The heat lamination was carried out under conditions of 0.5MPa, 80 ℃ and 1 minute. Thus, a film of a film thickness of 30 μm made of a dry film is formed on the printed wiring board so as to cover the conductor wiring.

Infrared spectroscopic analysis of the coating film was performed to obtain an IR spectrum.

Then, from the polyethylene terephthalate film, a negative mask having circular shielding portions with diameters of 30 μm, 45 μm and 60 μm and stripe-shaped shielding portions with a line width/pitch of 40 μm/40 μm was directly brought into contact with the film, and in this state, the film was coated at 300mJ/cm through the negative mask²The conditions (3) are irradiated with ultraviolet rays, thereby curing the exposed portion of the coating film to produce a cured film. Peeling the polyethylene terephthalate film from the cured filmAnd (5) separating.

Next, in each of examples and reference examples 1 to 9, the cured film was treated with an alkaline solution, and the unexposed portion of the coating film was removed with the alkaline solution. When treated, 1% Na at 30 ℃ was added₂CO₃The aqueous solution (pH11) was sprayed on the cured film at a spray pressure of 0.2MPa for 90 seconds. Subsequently, the cured film was rinsed by spraying pure water at a spray pressure of 0.2MPa for 90 seconds. Thus, an opening is formed in the cured film at a position where an unexposed portion is removed. On the other hand, in each of comparative examples and reference examples 10 to 18, the cured film was not treated with an alkaline solution.

(3-2) Heat treatment of cured film

In examples 1 to 27, comparative examples, and reference examples, the cured film was heated at 150 ℃ for 50 minutes. In example 28, the cured film was heated at 160 ℃ for 120 minutes. In example 29, the cured film was heated at 180 ℃ for 120 minutes.

Next, infrared spectroscopy of the cured film was performed to obtain an IR spectrum.

From 910cm in the IR spectrum of the coating^-1Normalized value (S) of the area of the peak of (1)₀) And 910cm in IR spectrum of the cured film^-1Normalized value (S) of the area of the peak of (1)₂) And according to (S)₀－S₂)÷S₀The reaction rate (percentage) of epoxy groups was calculated by the equation of X100 (%). The normalized value (S) is₀) Is measured from 910cm in the IR spectrum of the coating^-1Measured value of the area of the peak (P)₀) And 750cm^－1Measured value of the area of the peak (R)₀) And according to S₀＝P₀/R₀Normalized value (S) of the formula (c)₂) Is 910cm in the IR spectrum of the cured film^-1Measured value of the area of the peak (P)₂) And 750cm^－1Measured value of the area of the peak (R)₂) And according to S₂＝P₂/R₂The formula (c) is calculated. In addition, the decimal point of the calculation result of the reaction rate of the epoxy group is rounded first.

From the results, the reaction rates of the epoxy groups were classified as follows.

A: the reaction rate of the epoxy groups is less than 85 percent.

B: the reaction rate of the epoxy group is 85% or more and less than 90%.

C: the reaction rate of the epoxy group is 90% or more and less than 95%.

D: the reaction rate of the epoxy group is 95% or more.

Next, in each example, each comparative example, and each reference example, the cured film was irradiated with 1000mJ/cm using a high-pressure mercury lamp²Ultraviolet rays of (1).

(3-3) surface treatment of cured film

(3-3-1) Japanese (non-roughened) in examples 1 to 9 and 28 to 29 and comparative examples 1 to 9

The cured film was subjected to a cleaning treatment in the following manner. The cured film was immersed in a cleaning solution (a solution containing Cleaner securiganteh 902 with a concentration of 40ml/L, Cleaner addition 902 with a concentration of 3ml/L, and NaOH with a concentration of 20g/L, manufactured by Atotech Japan K.K.) at 60 ℃ for 5 minutes. Then, the cured film is coated with SnCl₂The aqueous solution (2) was immersed in the aqueous solution (0.1 g/L) for 3 minutes, and then washed with water. Next, the cured film was immersed in a liquid containing sodium persulfate at a concentration of 100g/L and sulfuric acid at a concentration of 10ml/L at 25 ℃ for 1 minute, and then washed with water.

(3-3-2) cases of examples 10 to 18 and comparative examples 10 to 18 (Low roughening)

The cured film was immersed in a 50 ℃ desmear Swelling solution (a solution containing 500mL/L of Swelling Dip securigant P and 3g/L of NaOH, manufactured by Atotech Japan K.K.) for 15 minutes to swell the film, and then the cured film was washed with hot water. Next, the cured film was immersed in a desmear solution containing potassium permanganate (a solution containing concentration Compact CP at a concentration of 580mL/L and NaOH at a concentration of 40g/L, manufactured by Atotech Japan K.K.) at50 ℃ for 10 minutes to roughen the surface of the cured film, and then washed with hot water. Subsequently, the cured film was immersed in a neutralizing solution (a solution containing 70mL/L reducing solution Securiganh P500 and 50mL/L sulfuric acid (98%) manufactured by Atotech Japan K.K.) at 40 ℃ for 5 minutes to remove the residue of the desmear solution on the surface of the cured film, followed by washing with water. Next, the cured film is subjected to a cleaning treatment in the same manner as in the case of the above item (4-1).

(3-3-3) cases (intermediate roughening) of examples 19 to 27 and comparative examples 19 to 27

The surface of the cured film was swollen by immersing it in a Swelling solution for desmearing (a solution containing Swelling Dip securigant P at a concentration of 500mL/L and NaOH at a concentration of 3g/L, manufactured by Atotech Japan K.K.) at 80 ℃ for 5 minutes, and then the cured film was washed with hot water. Next, the cured film was immersed in a desmear solution containing potassium permanganate (a solution containing concentration Compact CP at a concentration of 580mL/L and NaOH at a concentration of 40g/L, manufactured by Atotech Japan K.K.) at 60 ℃ for 5 minutes to roughen the surface of the cured film, followed by hot-water cleaning. Subsequently, the cured film was immersed in a neutralizing solution (a solution containing 70mL/L reducing solution Securiganh P500 and 50mL/L sulfuric acid (98%) manufactured by Atotech Japan K.K.) at 40 ℃ for 5 minutes to remove the residue of the desmear solution on the surface of the cured film, followed by washing with water. Next, the cured film is subjected to a cleaning treatment in the same manner as in the case of the above item (4-1).

(3-3-4) cases of reference examples 1 to 18 (high roughening)

The surface of the cured film was swollen by immersing it in a Swelling solution for desmearing (a solution containing Swelling Dip securigant P at a concentration of 500mL/L and NaOH at a concentration of 3g/Ln, manufactured by Atotech Japan K.K.) at 70 ℃ for 7.5 minutes, and then the cured film was washed with hot water. Next, the cured film was immersed in a desmear solution containing potassium permanganate (a solution containing concentration Compact CP at a concentration of 580mL/L and NaOH at a concentration of 40g/L, manufactured by Atotech Japan K.K.) at 70 ℃ for 7.5 minutes to roughen the surface of the cured film, and then washed with hot water. Subsequently, the cured film was immersed in a neutralizing solution (a solution containing 70mL/L reducing solution Securiganh P500 and 50mL/L sulfuric acid (98%) manufactured by Atotech Japan K.K.) at 40 ℃ for 5 minutes to remove the residue of the desmear solution on the surface of the cured film, followed by washing with water. Next, the cured film is subjected to a cleaning treatment in the same manner as in the case of the above item (4-1).

The surface roughness (arithmetic average roughness (Ra)) of the cured film in the test piece after the surface treatment was measured by a laser microscope. The results are classified as follows. The results are shown in the table.

A: the arithmetic average roughness (Ra) is less than 30 nm.

B: the arithmetic average roughness (Ra) is 30nm or more and less than 80 nm.

C: the arithmetic average roughness (Ra) is 80nm or more and less than 150 nm.

D: the arithmetic average roughness (Ra) is 150nm or more.

(4) Evaluation test

The following tests were carried out on the test pieces of the respective examples, comparative examples and reference examples. The results are shown in tables 2 to 10.

(4-1) copper plating adhesion

The cured film was subjected to electroless copper plating treatment (MV plus treatment by Atotech Japan K.K.), then heated at 150 ℃ for 1 hour, and then subjected to electroless copper plating treatment at 2A/dm²The electrolytic copper plating treatment was performed at a current density of (1) to thereby form a copper film having a thickness of 33 μm, and then the test piece was heated at 180 ℃ for 30 minutes. Thereby, a copper plating layer is formed on the cured film. The peel strength between the copper plating layer and the cured film was measured in accordance with JIS C6481, except for the case where bubbles were generated at least either during heating after the electroless copper plating treatment or during heating after the electrolytic copper plating treatment. From the results, the adhesion of the copper plating layer was evaluated as follows.

A: the peel strength of the copper plating layer is 0.2kN/m or more.

B: the peel strength of the copper plating layer is 0.1kN/m or more and less than 0.2 kN/m.

C: the peel strength of the copper plating layer is less than 0.1 kN/m.

D: bubbles are generated at least either during heating after the electroless copper plating treatment or during heating after the electrolytic copper plating treatment.

(4-2) Electrical insulation

The test piece was heated at 150 ℃ for 1 hour and further at 180 ℃ for 30 minutes, and then exposed to a test environment of 130 ℃ and 85% r.h. for 100 hours while applying a bias voltage of DC30V between comb-shaped electrodes in the conductor wiring of the test piece. The resistance value of the cured film between the comb-shaped electrodes in this test environment was continuously measured, and the results thereof were evaluated as follows.

A: the resistance value was always maintained at 10 for a period from the start of the test to the elapse of 100 hours⁶Omega or more.

B: the resistance value was always maintained at 10 from the start of the test until 85 hours had passed⁶Omega or more, but the resistance value is less than 10 before 100 hours from the start of the test⁶Ω。

C: the resistance value was always maintained at 10 from the start of the test until 70 hours had passed⁶Omega or more, but the resistance value is less than 10 before 85 hours from the start of the test⁶Ω。

D: the resistance value was less than 10 hours before 70 hours had passed from the start of the test⁶Ω。

(4-3) opening Property

The cured films of the examples, comparative examples, and reference examples were observed for a circular opening corresponding to the circular mask portion of the negative mask, and evaluated as follows.

A: the opening portions corresponding to the mask portions having diameters of 30 μm, 45 μm and 60 μm were formed.

B: the opening portions corresponding to the mask portions having a diameter of 30 μm were not formed, but the opening portions corresponding to the mask portions having diameters of 45 μm and 60 μm were formed.

C: the openings corresponding to the mask portions having diameters of 30 μm and 45 μm were not formed, but the openings corresponding to the mask portions having diameters of 60 μm were formed.

D: the opening portions corresponding to the mask portions having diameters of 30 μm, 45 μm and 60 μm were not formed.

(4-4) resolution

The cured films of the examples, comparative examples, and reference examples were observed for the striped openings corresponding to the striped shielding portions, and evaluated as follows.

A: the outline of the opening is not uneven, and clear and sharp resolution is exhibited.

B: the outline of the opening portion was observed to be somewhat uneven, but showed clear resolution.

C: unevenness in the outline of the opening was observed, and the resolution was slightly poor.

D: the profile of the opening is largely uneven, and the resolution is poor.

[ Table 2]

[ Table 3]

[ Table 4]

[ Table 5]

[ Table 6]

[ Table 7]

[ Table 8]

[ Table 9]

[ Table 10]

The embodiments described above show that: in the method for manufacturing a multilayer printed wiring board (20) according to embodiment 1 of the present invention, a coating film (4) is formed on the printed wiring board (1) from a photosensitive resin composition. The photosensitive resin composition contains a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, a photopolymerization initiator (C), and an epoxy compound (D). A cured film (11) is produced by photocuring the coating film (4). The cured film (11) is treated with an alkaline solution, and then a conductor layer (8) in contact with the cured film (11) is produced. The arithmetic mean roughness Ra specified in JIS B0601-2001 of the surface of the cured film (11) in contact with the conductor layer (8) immediately before the conductor layer (8) is produced is less than 150 nm.

According to the first aspect, a multilayer printed wiring board (20) that can achieve high adhesion between the interlayer insulating layer (7) and the conductor layer (8) can be obtained without roughening or with a small degree of roughening the interlayer insulating layer (7) comprising the cured film (11).

In the method for manufacturing a multilayer printed wiring board (20) according to embodiment 2 of the present invention, in embodiment 1, the arithmetic mean roughness Ra is less than 80 nm.

According to the 2 nd aspect, the multilayer printed wiring board (20) can have good high-frequency characteristics.

In the method for manufacturing a multilayer printed wiring board (20) according to embodiment 3 of the present invention, in embodiment 1 or 2, the curing film (11) is not subjected to a heat treatment until the conductor layer (8) is formed after the curing film (11) is formed, or the heat treatment is performed so that the reaction rate of epoxy groups based on the coating film (4) is less than 95%.

According to the embodiment 3, the adhesion between the interlayer insulating layer 7 and the conductor layer 8, which are formed of the cured film 11, can be improved.

In the method for manufacturing a multilayer printed wiring board (20) according to embodiment 4 of the present invention, in any of embodiments 1 to 3, the photosensitive resin composition is a dry film.

According to the 4 th aspect, a multilayer printed wiring board (20) that can achieve high adhesion between the interlayer insulating layer (7) and the conductor layer (8) can be obtained without roughening or with a small degree of roughening the interlayer insulating layer (7) formed of the cured film (11).

In the method for producing a multilayer printed wiring board (20) according to embodiment 5 of the present invention, in any of embodiments 1 to 4, the photosensitive resin composition further contains an organic filler (E).

According to the 5 th aspect, the adhesion between the interlayer insulating layer (7) formed of the cured film (11) and the conductor layer (8) is improved.

In the method for producing a multilayer printed wiring board (20) according to embodiment 6 of the present invention, in embodiment 5, the organic filler (E) has a polar group.

According to the 6 th aspect, the adhesion between the interlayer insulating layer (7) formed of the cured film (11) and the conductor layer (8) is further improved.

In the method for producing a multilayer printed wiring board (20) according to embodiment 7 of the present invention, in embodiment 6, the polar group contains at least one group selected from a carboxyl group, an amino group and a hydroxyl group.

According to the 7 th aspect, the adhesion between the interlayer insulating layer (7) formed of the cured film (11) and the conductor layer (8) is particularly improved.

In the method for producing a multilayer printed wiring board (20) according to embodiment 8 of the present invention, in any of embodiments 5 to 7, the particle diameter of the organic filler (E) in the photosensitive resin composition is 10 μm or less. The adhesion between the interlayer insulating layer (7) composed of the cured film (11) and the conductor layer (8) is particularly improved.

According to the 8 th aspect, the adhesion between the interlayer insulating layer (7) formed of the cured film (11) and the conductor layer (8) is particularly improved.

In the method for manufacturing a multilayer printed wiring board (20) according to claim 9 of the present invention, in any one of embodiments 1 to 8, the curing film (11) is not subjected to a treatment with an oxidizing agent during a period from the time when the curing film (11) is produced to the time when the conductor layer (11) is produced.

According to the 9 th aspect, the roughness of the cured film (11) due to the oxidizing agent is prevented, and the arithmetic mean roughness Ra of the cured film (11) is easily made smaller than 150 nm.

A multilayer printed wiring board (20) according to claim 10 is produced by the production method according to any one of claims 1 to 9.

According to the 10 th aspect, a multilayer printed wiring board (20) having high adhesion between the interlayer insulating layer (7) and the conductor layer (8) can be obtained.

Description of the symbols

1 printed wiring board

4 coating film

7 interlayer insulating layer

8 conductive layer

11 cured film

20 multilayer printed wiring board

Claims

1. A method for manufacturing a multilayer printed wiring board, comprising forming a coating film on a printed wiring board from a photosensitive resin composition,

the photosensitive resin composition comprises a carboxyl group-containing resin (A), an unsaturated compound (B) having at least one ethylenically unsaturated bond in one molecule, a photopolymerization initiator (C) and an epoxy compound (D),

the solid acid value of the carboxyl group-containing resin (A) is in the range of 40mgKOH/g to 160mgKOH/g,

the amount of the carboxyl group-containing resin (A) is in the range of 5 to 85 mass% relative to the amount of the solid component of the photosensitive resin composition,

a cured film is produced by photocuring the coating film,

treating the cured film with an alkaline solution to prepare a conductor layer in contact with the cured film,

performing a heat treatment on the cured film so that a reaction rate of epoxy groups based on the coating film is less than 95% during a period from when the cured film is produced to when the conductor layer is produced,

the arithmetic mean roughness Ra specified in JIS B0601-2001 of the surface of the cured film in contact with the conductor layer immediately before the conductor layer is produced is less than 150 nm.

2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the arithmetic average roughness Ra is less than 80 nm.

3. The method for manufacturing a multilayer printed wiring board according to claim 1 or 2, wherein the photosensitive resin composition is a dry film.

4. The method for producing a multilayer printed wiring board according to claim 1 or 2, wherein the photosensitive resin composition further contains an organic filler (E).

5. The method for manufacturing a multilayer printed wiring board according to claim 4, wherein the organic filler (E) has a polar group.

6. The method for manufacturing a multilayer printed wiring board according to claim 5, wherein the polar group contains at least one group selected from a carboxyl group, an amino group, and a hydroxyl group.

7. The method for producing a multilayer printed wiring board according to claim 4, wherein the particle diameter of the organic filler (E) in the photosensitive resin composition is 10 μm or less.

8. The method for manufacturing a multilayer printed wiring board according to claim 1 or 2, wherein the curing film is not treated with an oxidizing agent during a period from the time when the curing film is manufactured to the time when the conductor layer is manufactured.

9. A multilayer printed wiring board produced by the production method according to any one of claims 1 to 8.