CN113166410A

CN113166410A - Photosensitive thermosetting resin composition, dry film and printed wiring board

Info

Publication number: CN113166410A
Application number: CN201980077434.2A
Authority: CN
Inventors: 宫部英和; 米田一善
Original assignee: Taiyo Ink Mfg Co Ltd
Current assignee: Taiyo Holdings Co Ltd
Priority date: 2018-11-30
Filing date: 2019-11-08
Publication date: 2021-07-23
Also published as: WO2020110671A1; KR20210097131A; JP2020086387A; TW202032271A

Abstract

Providing: a photosensitive thermosetting resin composition, a dry film and a printed wiring board which can be developed with a weakly alkaline aqueous solution of sodium carbonate and are excellent in photosensitivity, heat resistance, flexibility and other mechanical properties. Light sensitivityA thermosetting resin composition characterized by comprising: (A) an alkali-soluble polyamideimide resin, (B) a resin having an unsaturated double bond and a carboxyl group, (C) a thermosetting cyclic ether group-containing compound, and (D) a photopolymerization initiator, wherein the alkali-soluble polyamideimide resin (A) is a polyamideimide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2). (X)₁Is a residue of aliphatic diamine (a) derived from a dimer acid having 24 to 48 carbon atoms, X₂Is a residue of an aromatic diamine (b) having a carboxyl group, and each Y is independently a cyclohexane ring or an aromatic ring. )

Description

Photosensitive thermosetting resin composition, dry film and printed wiring board

Technical Field

The present invention relates to a photosensitive thermosetting resin composition (hereinafter, also simply referred to as "resin composition"), a dry film and a printed wiring board, which can be developed with an aqueous alkali solution and which can provide a cured film having excellent physical properties.

Background

In recent years, printed circuit board technology has been successfully and remarkably developed with the miniaturization and weight reduction of electronic devices, and the demand for solder resists to be used has been increasing.

On the other hand, an alkali development type photosensitive resin composition which can be developed with an alkali aqueous solution due to the trend of miniaturization of a solder resist is mainstream, and characteristics such as heat resistance, flexibility, low dielectric characteristics and the like are added according to each application.

As a method for forming a solder resist using such an alkali development type photosensitive resin composition, the following methods are generally used: the photosensitive resin composition is applied to a substrate, dried to form a resin layer, and the resin layer is formed by irradiating the resin layer with light in a pattern form and then developing the resin layer in an alkali developing solution.

In the method for forming a solder resist, an alkali developing solution may be sodium carbonate (Na)₂CO₃) Aqueous solution, aqueous potassium carbonate solution (K)₂CO₃) And an aqueous alkali solution such as an aqueous sodium hydroxide (NaOH) solution and a tetramethylammonium hydroxide (TMAH) solution. These alkalisIn the production of printed wiring boards, an aqueous solution of weakly basic sodium carbonate or potassium carbonate is generally used in terms of reliability of substrates and working environment. Therefore, it is extremely important that the photosensitive resin composition for printed wiring boards can be developed in a weakly alkaline aqueous solution of sodium carbonate or the like.

Conventionally, the type of resin used in a photosensitive resin composition has been selected appropriately in order to exhibit coating film characteristics satisfying various requirements. In particular, it is difficult to achieve both of developability with an alkaline aqueous solution and curing properties, and even when the purpose of providing the properties is to be achieved, there is a possibility that development cannot be performed with a weakly alkaline aqueous sodium carbonate solution or the like depending on the type of resin. For example, when a polyimide resin or a polyamideimide resin containing an imide ring is used to improve heat resistance, the composition is excellent in mechanical properties and heat resistance due to its structure, but it is often difficult to apply the composition to development using a sodium carbonate aqueous solution. In this regard, in the example of patent document 1 which discloses the invention relating to the photosensitive resin composition containing the polyimide resin, it is also known that the development is performed by a strongly alkaline aqueous solution of sodium hydroxide.

Conventionally, it has been studied to impart developability to these polyimide resins and polyamideimide resins, but in order to impart developability, it is necessary to deal with this by greatly sacrificing the mechanical properties specific to the imide.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2004-317725

Further, as the device becomes more functional, the circuit design of the printed circuit board becomes more complicated. For example, in the past, substrates having a high circuit thickness have been used for substrates for mounting on vehicles, power supply substrates for various devices, and the like, and further, there has been a background that the wiring pitch has been gradually decreased. Therefore, it is not to say that the embeddability between circuits greatly changes, and the thickness of the solder resist greatly changes both on the circuits and between the circuits, and therefore, it is difficult to gradually control the patterning by the alkali development. That is, since the solder resist becomes thin on the circuit and becomes thick between the circuits, if the light curing condition is set for the thin film portion, a deep curing defect occurs in the thick film portion, and conversely, if the light curing condition is set for the thick film portion, a shadow is caused in the thin film portion, and a problem of no opening is caused.

Further, in the conventional solder resist, the hiding property of the coating film is exhibited by the coloring pigment, and the hiding property varies depending on the concentration of the coloring pigment contained in the coating film, so that there arises a problem that the shade occurs in the same substrate in the case of the circuit design having a high circuit thickness as described above. That is, a thick film portion exhibits high covering properties, while a thin film portion on a circuit or the like has low covering properties, and therefore, a phenomenon that particularly a circuit edge portion is transparent is often seen. In order to solve such in-plane shading, the pigment concentration in the composition is usually adjusted, but the photosensitivity may be hindered, and the practical application to an alkali-developable photosensitive resin composition is limited.

Disclosure of Invention

Problems to be solved by the invention

Accordingly, an object of the present invention is to solve the above problems and provide: a photosensitive thermosetting resin composition and a dry film, and a printed wiring board using the same, which are excellent in photosensitivity, alkali developability, and mechanical properties such as heat resistance, and which provide a cured product having a coating film with a good covering property independent of a difference in film thickness due to circuit design.

Means for solving the problems

The present inventors have conducted intensive studies in order to achieve the above object. As a result, the cured coating film is not provided with hiding properties only by the colored pigment, but the above-mentioned problems are solved by utilizing the refractive index change during curing.

Namely, it was found that: a coating film of a photosensitive resin composition is capable of being photocured to a deep pigment concentration and transparency while maintaining the pigment concentration and transparency at the time of exposure which affect photocurability, and the refractive index of the coating film is changed at the time of thermal curing after development, whereby the cured coating film shows uniform covering properties without in-plane fluctuation.

More specifically, it was found that: the present inventors have found that the above-mentioned problems of mechanical properties and developability are solved by using a photosensitive thermosetting resin composition containing a polyamideimide resin having a specific structure, and further, that a composition containing the polyamideimide resin, a thermosetting cyclic ether group-containing compound, a resin having an unsaturated double bond and a carboxyl group, and a photopolymerization initiator improves the covering properties of a cured coating film after photocuring and thermosetting, and that uniform covering properties can be obtained without in-plane fluctuation in the cured coating film, and thus the present invention has been completed.

That is, the photosensitive thermosetting resin composition of the present invention is characterized by comprising:

(A) an alkali-soluble polyamideimide resin,

(B) A resin having an unsaturated double bond and a carboxyl group,

(C) A thermosetting cyclic ether group-containing compound, and

(D) a photopolymerization initiator,

the alkali-soluble polyamideimide resin (A) is a polyamideimide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2),

(X₁is a residue of aliphatic diamine (a) derived from a dimer acid having 24 to 48 carbon atoms, X₂Is a residue of an aromatic diamine (b) having a carboxyl group, and each Y is independently a cyclohexane ring or an aromatic ring. ).

In the photocurable thermosetting resin composition of the present invention, the mass average molecular weight Mw of the polyamideimide resin (a) is preferably 20000 or less. Further, it is preferable that the photopolymerization initiator (D) includes: and also as a photopolymerization initiator functioning as a photobase generator.

The dry film of the present invention is characterized by having a resin layer formed from the photosensitive thermosetting resin composition of the present invention.

Further, the printed wiring board of the present invention is characterized by comprising a cured product formed by using the photosensitive thermosetting resin composition of the present invention or the dry film of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, there can be provided: a photosensitive thermosetting resin composition, a dry film and a printed wiring board are obtained which are excellent in photosensitivity, alkali developability (developability with a weak alkali aqueous solution), and further excellent in mechanical properties such as heat resistance, and which are free from a difference in film thickness caused by circuit design in the covering property of a coating film.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail.

The photosensitive thermosetting resin composition of the present invention is characterized by containing: (A) an alkali-soluble polyamideimide resin, (B) a resin having an unsaturated double bond and a carboxyl group, (C) a thermosetting cyclic ether group-containing compound, and (D) a photopolymerization initiator,

As described above, in a conventional solder resist, the hiding property of a coating film is exhibited by a coloring pigment, and the hiding property varies depending on the concentration of the coloring pigment contained in the coating film, so that a circuit board having a high circuit thickness exhibits a high hiding property as a thick film portion of a base material portion (between circuits), while a thin film portion on a circuit or the like has a low hiding property, and thus, a phenomenon occurs in which particularly a circuit edge portion is transparent.

The photosensitive thermosetting resin composition of the present invention has the greatest features in the following constitutions: a specific alkali-soluble polyamideimide resin (a) containing an aliphatic unit derived from a dimer acid and a carboxyl group is used, and a resin (B) having an unsaturated double bond and a carboxyl group, and a thermosetting cyclic ether group-containing compound (C) are used. By forming such a constitution, the pigment concentration and transparency at the deep part of the cured film can be maintained at the time of exposure which affects photocurability, and the refractive index of the cured film is changed at the time of thermal curing after development, whereby the cured film can exhibit uniform covering properties without in-plane fluctuation. That is, a photosensitive thermosetting resin composition having good resolution, having a coating film with good hiding property independent of a difference in film thickness due to circuit design, excellent in photosensitivity and alkali developability, and further excellent in mechanical properties such as heat resistance can be obtained.

The components constituting the photosensitive thermosetting resin composition of the present invention will be described in detail below.

[ (A) alkali-soluble polyamideimide resin ]

In the curable resin composition of the present invention, as the alkali-soluble polyamideimide resin, a polyamideimide resin having a structure represented by the following general formula (1) and a structure represented by the following general formula (2) is used. Thereby, the developability can be further improved.

Here, X₁Is a residue of an aliphatic diamine (a) (also referred to as "dimer diamine (a)" in the present specification) derived from a dimer acid having 24 to 48 carbon atoms. X₂Is a residue of an aromatic diamine (b) having a carboxyl group (also referred to as "carboxyl group-containing diamine (b)" in the present specification). Each Y is independently a cyclohexane ring or an aromatic ring.

By including the structure represented by the general formula (1) and the structure represented by the general formula (2), a polyamideimide resin having excellent alkali solubility, which is soluble even in the case of using a mild alkali solution such as a 1.0 mass% sodium carbonate aqueous solution, can be formed. In addition, a cured product of the resin composition containing the polyamideimide resin may have excellent dielectric characteristics.

The dimer diamine (a) can be obtained by reductively aminating a carboxyl group in a dimer of an aliphatic unsaturated carboxylic acid having 12 to 24 carbon atoms. That is, the dimer diamine (a) which is an aliphatic diamine derived from a dimer acid can be obtained, for example, as follows: unsaturated fatty acids such as oleic acid and linoleic acid are polymerized to form dimer acid, which is reduced and aminated to obtain the dimer acid. As such an aliphatic diamine, for example, diamines having a carbon number of 36 as backbones, i.e., commercially available products such as primamine 1073, 1074, and 1075 (trade name, manufactured by Croda Japan corporation) can be used. The dimer diamine (a) may be derived from a dimer acid having 28 to 44 carbon atoms, and may be derived from a dimer acid having 32 to 40 carbon atoms.

Specific examples of the carboxyl group-containing diamine (b) include 3, 5-diaminobenzoic acid, 3, 4-diaminobenzoic acid, 5 '-methylenebis (anthranilic acid), benzidine-3, 3' -dicarboxylic acid, and the like. The carboxyl group-containing diamine (b) may be composed of 1 kind of compound or may be composed of a plurality of kinds of compounds. The carboxyl group-containing diamine (b) preferably contains 3, 5-diaminobenzoic acid and 5, 5' -methylenebis (anthranilic acid) from the viewpoint of availability of raw materials.

The relationship between the content of the structure represented by the general formula (1) and the content of the structure represented by the general formula (2) in the polyamide-imide resin is not limited. The content (unit: mass%) of the dimer diamine (a) is preferably 20 to 60 mass%, more preferably 30 to 50 mass%, from the viewpoint of improving the balance between the alkali solubility of the polyamideimide resin and other properties such as mechanical properties of a cured product of the resin composition containing the polyamideimide resin. In the present specification, the "content of the dimer diamine (a)" refers to a ratio of an amount of the dimer diamine (a) to be charged, which is one of raw materials for producing the polyamide imide resin, to a mass of the produced polyamide imide resin. Here, "the mass of the produced polyamideimide resin" means that the amount of all raw materials used to produce the polyamideimide resin is subtracted by water (H) generated by imidization₂O) and carbon dioxide gas (CO) produced by amidation₂) The theoretical amount of (c).

From the viewpoint of improving the alkali solubility of the polyamideimide resin, the moiety represented by Y in the above general formula (1) and the above general formula (2) preferably has a cyclohexane ring. In the relationship between the amounts of the aromatic ring and the cyclohexane ring in the portion represented by Y, the molar ratio of the content of the cyclohexane ring to the content of the aromatic ring is preferably 85/15 to 100/0, more preferably 90/10 to 99/1, and still more preferably 90/10 to 98/2, from the viewpoint of improving the balance between the alkali solubility of the polyamideimide resin and other properties such as mechanical properties of a cured product of a resin composition containing the polyamideimide resin.

The polyamideimide resin may further have a partial structure represented by the following general formula (i).

Here, X₃Is a residue of a dimer diamine (a) and a diamine (f) other than the carboxyl group-containing diamine (b) (also referred to as "other diamine (f)" in the present specification), and Y is independently an aromatic ring or a cyclohexane ring, as in the general formula (1) and the general formula (2). The other diamine (f) may be composed of 1 kind of compound or may be composed of a plurality of kinds of compounds.

Specific examples of the other diamine (f) include 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane, bis [4- (3-aminophenoxy) phenyl ] sulfone, bis [4- (4-aminophenoxy) phenyl ] sulfone, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl ] methane, 4 '-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl ] ether, bis [4- (4-aminophenoxy) phenyl ] ketone, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 2' -dimethylbiphenyl-4, aromatic diamines such as 4 '-diamine, 2' -bis (trifluoromethyl) biphenyl-4, 4 '-diamine, 2,6, 2', 6 '-tetramethyl-4, 4' -diamine, 5 '-dimethyl-2, 2' -sulfonyl-biphenyl-4, 4 '-diamine, 3' -dihydroxybiphenyl-4, 4 '-diamine, (4, 4' -diamino) diphenyl ether, (4,4 '-diamino) diphenyl sulfone, (4, 4' -diamino) benzophenone, (3,3 '-diamino) benzophenone, (4, 4' -diamino) diphenylmethane, (4,4 '-diamino) diphenyl ether, and (3, 3' -diamino) diphenyl ether, examples thereof include aliphatic diamines such as hexamethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, octadecamethylenediamine, 4' -methylenebis (cyclohexylamine), isophoronediamine, 1, 4-cyclohexanediamine, and norbornenediamine.

The polyamideimide resin may have a structure represented by the following general formula (ii).

Here, Z may be an aliphatic group or an aromatic group. When the group is an aliphatic group, an alicyclic group such as a cyclohexane ring may be included. According to the production method described later, Z is a residue of the diisocyanate compound (e).

The method for producing the polyamide-imide resin is not limited, and the polyamide-imide resin can be produced by a known and commonly used method through an imidization step and an amide imidization step.

In the imidization step, the dimer diamine (a), the carboxyl group-containing diamine (b), and 1 or 2 kinds selected from the group consisting of cyclohexane-1, 2, 4-tricarboxylic acid-1, 2-anhydride (c) and trimellitic anhydride (d) are reacted to obtain an imidized material.

The amount of the dimer diamine (a) to be added is preferably 20 to 60 mass%, more preferably 30 to 50 mass%. The content of the dimer diamine (a) is as defined above.

If necessary, the other diamine (f) may be used together with the dimer diamine (a) and the carboxyl group-containing diamine (b).

In the imidization step, cyclohexane-1, 2, 4-tricarboxylic acid-1, 2-anhydride (c) is preferably used from the viewpoint of improving the alkali solubility of the polyamideimide resin. The molar ratio of the amount of the cyclohexane-1, 2, 4-tricarboxylic acid-1, 2-anhydride (c) to the amount of the trimellitic anhydride (d) is preferably 85/15 to 100/0, more preferably 90/10 to 99/1, and still more preferably 90/10 to 98/2.

The relationship between the amount of the diamine compound (specifically, dimer diamine (a), carboxyl group-containing diamine (b) and other diamine (f) used as needed) used for obtaining the imide compound and the amount of the acid anhydride (specifically, 1 or 2 selected from the group consisting of cyclohexane-1, 2, 4-tricarboxylic acid-1, 2-anhydride (c) and trimellitic anhydride (d)) is not limited. The amount of the acid anhydride to be used is preferably an amount of 2.0 to 2.4 mol based on the amount of the diamine compound to be used, and more preferably an amount of 2.0 to 2.2 mol.

In the amide imidization step, the imide compound obtained in the imidization step is reacted with a diisocyanate compound (e) to obtain a polyamideimide resin containing a substance having a structure represented by the following general formula (3).

The specific kind of the diisocyanate compound (e) is not limited. The diisocyanate compound (e) may be composed of 1 kind of compound or may be composed of a plurality of kinds of compounds.

Specific examples of the diisocyanate compound (e) include aromatic diisocyanates such as 4, 4' -diphenylmethane diisocyanate, 2, 4-tolylene diisocyanate, 2, 6-tolylene diisocyanate, naphthalene-1, 5-diisocyanate, o-xylylene diisocyanate, m-xylylene diisocyanate, and 2, 4-tolylene diisocyanate dimer; aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and norbornene diisocyanate. From the viewpoint of improving both the alkali solubility of the polyamideimide resin and the transparency of the polyamideimide resin, the diisocyanate compound (e) preferably contains an aliphatic isocyanate, and the diisocyanate compound (e) is more preferably an aliphatic isocyanate.

The amount of the diisocyanate compound (e) used in the amide imidization step is not limited. From the viewpoint of imparting a suitable alkali solubility to the polyamideimide resin, the amount of the diisocyanate compound (e) to be used is preferably 0.3 or more and 1.0 or less, more preferably 0.4 or more and 0.95 or less, and particularly preferably 0.50 or more and 0.90 or less in terms of a molar ratio relative to the amount of the diamine compound used for obtaining the imide compound.

The polyamideimide resin thus produced contains a substance having a structure represented by the following general formula (3).

In the general formula (3), each X is independently a diamine residue (residue of a diamine compound), each Y is independently an aromatic ring or a cyclohexane ring, and Z is a residue of a diisocyanate compound. n is a natural number.

The alkali-soluble polyamideimide resin described above has an acid value of preferably 50mgKOH/g or more, more preferably 50 to 200mgKOH/g, and even more preferably 70 to 130mgKOH/g, from the viewpoint of improving the balance between the alkali solubility (developability) of the polyamideimide resin and other properties such as mechanical properties of a cured product of a resin composition containing the polyamideimide resin. When the acid value is 50mgKOH/g or more, the solubility to alkali increases, the developability becomes good, and further, the degree of crosslinking with a thermosetting component after light irradiation becomes high, and therefore, a sufficient development contrast can be obtained. On the other hand, if the acid value is 200mgKOH/g or less, accurate drawing of a pattern becomes easy.

In addition, the molecular weight of the alkali-soluble polyamideimide resin is preferably 20000 or less, more preferably 1000 to 15000, and further preferably 2000 to 10000, in view of developability and cured coating film characteristics. When the molecular weight is 20000 or less, the alkali solubility of the unexposed portion increases, and the developability improves. On the other hand, when the molecular weight is 1000 or more, sufficient development resistance and curing properties can be obtained in the exposed portion.

[ (B) resin having unsaturated double bond and carboxyl group ]

Examples of the resin having an unsaturated double bond and a carboxyl group include the following compounds (both oligomers and polymers).

(1) The carboxyl group-containing photosensitive polyurethane resin is obtained by addition polymerization of a diisocyanate such as an aliphatic diisocyanate, a branched aliphatic diisocyanate, an alicyclic diisocyanate, or an aromatic diisocyanate, a carboxyl group-containing diol compound such as dimethylolpropionic acid or dimethylolbutyric acid, and a diol compound such as a polycarbonate-based polyol, a polyether-based polyol, a polyester-based polyol, a polyolefin-based polyol, an acrylic polyol, a bisphenol a-based alkylene oxide adduct diol, or a compound having a phenolic hydroxyl group and an alcoholic hydroxyl group.

(2) A carboxyl group-containing photosensitive polyurethane resin obtained by addition polymerization of a diisocyanate, a (meth) acrylate ester of a 2-functional epoxy resin such as a bisphenol A epoxy resin, a hydrogenated bisphenol A epoxy resin, a bisphenol F epoxy resin, a bisphenol S epoxy resin, a bixylenol epoxy resin, or a diphenol epoxy resin, or a partial acid anhydride modification thereof, with a carboxyl group-containing diol compound.

(3) A carboxyl group-containing photosensitive resin obtained by reacting a 2-functional or higher polyfunctional (solid) epoxy resin with (meth) acrylic acid to add a dibasic acid anhydride to a hydroxyl group present in a side chain.

(4) A carboxyl group-containing photosensitive resin obtained by further epoxidizing the hydroxyl group of a 2-functional (solid) epoxy resin with epichlorohydrin to obtain a polyfunctional epoxy resin, reacting the obtained polyfunctional epoxy resin with (meth) acrylic acid, and adding a dibasic acid anhydride to the resulting hydroxyl group.

(5) A carboxyl group-containing photosensitive resin obtained by reacting a compound having a plurality of phenolic hydroxyl groups in 1 molecule with an alkylene oxide such as ethylene oxide or propylene oxide or a cyclic carbonate compound to obtain a reaction product, reacting the obtained reaction product with an unsaturated group-containing monocarboxylic acid, and further reacting the obtained reaction product with a polybasic acid anhydride.

(6) A carboxyl group-containing photosensitive resin obtained by adding an ethylenically unsaturated group to a1 or more copolymer of an unsaturated carboxylic acid such as (meth) acrylic acid and a compound having an unsaturated double bond other than the unsaturated carboxylic acid in the form of a side chain, with a compound having an epoxy group and an unsaturated double bond, a (meth) acryloyl chloride, or the like.

(7) And (2) a carboxyl group-containing photosensitive resin obtained by further adding a compound having 1 epoxy group and 1 or more (meth) acryloyl groups in 1 molecule to the resins (1) to (6).

These (B) components can be used alone in 1 kind, or can be combined with 2 or more kinds and use.

The amount of the component (B) in the photosensitive thermosetting resin composition of the present invention is preferably 5 to 150 parts by mass, more preferably 10 to 80 parts by mass, based on 100 parts by mass of the polyamideimide resin (a). By setting the amount of component (B) to the above range, it becomes possible to achieve both the improvement of the development resistance in the exposed portion and the securing of the developability in the unexposed portion.

[ (C) thermosetting cyclic ether group-containing Compound ]

The thermosetting cyclic (thio) ether group-containing compound is a compound having in the molecule any one or 2 kinds of groups of a cyclic ether group or a cyclic thioether group having a plurality of 3-membered, 4-membered or 5-membered rings, and examples thereof include epoxy resins, oxetane compounds and episulfide resins.

Examples of the epoxy resin include bisphenol a type epoxy resin, brominated epoxy resin, novolac type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol a type epoxy resin, glycidyl amine type epoxy resin, hydantoin type epoxy resin, alicyclic epoxy resin, trishydroxyphenylmethane type epoxy resin, bixylenol type or biphenol type epoxy resin, or a mixture thereof; bisphenol S type epoxy resins, bisphenol a novolac type epoxy resins, heterocyclic epoxy resins, biphenol novolac type epoxy resins, naphthyl-containing epoxy resins, epoxy resins having a dicyclopentadiene skeleton, and the like.

Examples of oxetane compounds include bis [ (3-methyl-3-oxetanylmethoxy) methyl ] ether, bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] ether, 1, 4-bis [ (3-methyl-3-oxetanylmethoxy) methyl ] benzene, 1, 4-bis [ (3-ethyl-3-oxetanylmethoxy) methyl ] benzene, (3-methyl-3-oxetanyl) methyl acrylate, (3-ethyl-3-oxetanyl) methyl acrylate, (3-methyl-3-oxetanyl) methyl methacrylate, (3-ethyl-3-oxetanyl) methyl methacrylate, and mixtures thereof, In addition to polyfunctional oxetanes such as oligomers and copolymers thereof, there may be mentioned etherates of oxetanol and hydroxyl group-containing resins such as novolak resins, poly (p-hydroxystyrene), Cardo-type bisphenols, calixarenes, and silsesquioxanes. Further, a copolymer of an unsaturated monomer having an oxetane ring and an alkyl (meth) acrylate, and the like can be mentioned.

Examples of the episulfide resin include YL7000 (bisphenol A type episulfide resin) manufactured by Mitsubishi chemical corporation. Alternatively, an episulfide resin or the like obtained by replacing an oxygen atom of an epoxy group of a novolac epoxy resin with a sulfur atom by the same synthesis method can be used.

These (C) thermosetting cyclic ether group-containing compounds may be used alone in 1 kind, or may be used in combination with 2 or more kinds.

The amount of the thermosetting cyclic ether group-containing compound (C) to be blended in the photosensitive thermosetting resin composition of the present invention is an amount in which the ratio of the thermosetting cyclic ether group equivalent to the carboxylic acid equivalent of the total of the component (a) and the component (B) is preferably in the range of 0.2 to 3.0, more preferably 0.5 to 2.0.

[ (D) photopolymerization initiator ]

As the photopolymerization initiator (D) used in the present invention, publicly known ones can be used, and particularly, a photopolymerization initiator having a function as a photobase generator is suitable when used in a heating (PEB) step after light irradiation described later. When the heating step is performed after the exposure, a photopolymerization initiator may be used in combination with a photobase generator.

The photopolymerization initiator also having a function as a photobase generator is a compound as follows: the molecular structure is changed or the molecules are cleaved by irradiation with light such as ultraviolet light or visible light, and 1 or more kinds of basic substances capable of functioning as a catalyst for the polymerization reaction of the (C) thermosetting cyclic ether group-containing compound as the thermally reactive compound are generated. Examples of the basic substance include secondary amines and tertiary amines.

Examples of the photopolymerization initiator having such a function as a photobase generator include α -aminoacetophenone compounds, oxime ester compounds, compounds having a substituent such as an acyloxyimino group, an N-formylated aromatic amino group, an N-acylated aromatic amino group, a nitrobenzylcarbamate group, or an alkoxybenzylcarbamate group. Among these compounds, oxime ester compounds and α -aminoacetophenone compounds are preferable, and oxime ester compounds are more preferable. As the α -aminoacetophenone compound, a compound having 2 or more nitrogen atoms is particularly preferable.

The α -aminoacetophenone compound may have a benzoin ether bond in the molecule, and when irradiated with light, may be cleaved in the molecule to generate a basic substance (amine) exhibiting a curing catalytic action. Examples of the α -aminoacetophenone compound include Irgacure-907, Irgacure-369, and Irgacure-379 commercially available from BASF Japan.

Any oxime ester compound can be used as long as it generates a basic substance by light irradiation. Examples of such oxime ester compounds include commercially available CGI-325, Irgacure-OXE01, Irgacure-OXE02, N-1919, and NCI-831 manufactured by BASF Japan. Further, a photopolymerization initiator having 2 oxime ester groups in the molecule can also be suitably used.

Such photopolymerization initiators may be used alone in 1 kind, or may be used in combination with 2 or more kinds. The amount of the photopolymerization initiator in the resin composition is preferably 0.1 to 40 parts by mass, more preferably 0.3 to 20 parts by mass, per 100 parts by mass of the polyamideimide resin (a). When the amount is 0.1 parts by mass or more, the contrast of the development resistance between the irradiated portion and the non-irradiated portion can be obtained satisfactorily. In addition, when 40 parts by mass or less, the cured product properties are improved.

The photosensitive thermosetting resin composition of the present invention may contain the following components as necessary.

(monomer having unsaturated double bond)

In the resin composition of the present invention, a known monomer having an unsaturated double bond may be blended for the purpose of improving photoreactivity. Examples of such a monomer having an unsaturated double bond include commonly known polyester (meth) acrylate, polyether (meth) acrylate, urethane (meth) acrylate, carbonate (meth) acrylate, and epoxy (meth) acrylate. Specific examples thereof include hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; diacrylates of glycols such as ethylene glycol, polyethylene glycol, and propylene glycol; polyhydric alcohols such as hexanediol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tris-hydroxyethyl isocyanurate, and polyvalent acrylates such as ethylene oxide adducts, propylene oxide adducts, and epsilon-caprolactone adducts thereof; polyvalent acrylates such as phenoxy acrylate, bisphenol a diacrylate, and ethylene oxide adducts or propylene oxide adducts of these phenols; polyacrylates of glycidyl ethers such as glycerol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and at least one of various methacrylic acid esters corresponding to the above acrylic acid esters.

(Polymer resin)

The resin composition of the present invention may contain a known and commonly used polymer resin for the purpose of improving flexibility and finger-touch dryness of the resulting cured product. Examples of such a polymer resin include cellulose-based, polyester-based, phenoxy resin-based polymers, polyvinyl acetal-based, polyvinyl butyral-based, block copolymers, and elastomers. The polymer resin may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

(inorganic Filler)

The resin composition of the present invention may contain an inorganic filler in order to suppress curing shrinkage of a cured product and improve properties such as adhesion and hardness. Examples of such inorganic fillers include barium sulfate, amorphous silica, fused silica, spherical silica, talc, clay, magnesium carbonate, calcium carbonate, alumina, aluminum hydroxide, silicon nitride, aluminum nitride, boron nitride, and noniobar silica.

(coloring agent)

The resin composition of the present invention may contain a known and commonly used colorant. As the colorant, conventionally known colorants such as red, blue, green, yellow, white, and black can be used, and any of pigments, dyes, and pigments can be used.

(organic solvent)

In the resin composition of the present invention, an organic solvent may be used for preparing the resin composition and for adjusting the viscosity for application to a substrate or a carrier film. Examples of such organic solvents include ketones, aromatic hydrocarbons, glycol ethers, glycol ether acetates, esters, alcohols, aliphatic hydrocarbons, petroleum solvents, and the like. Such an organic solvent may be used alone in 1 kind, or may be used as a mixture of 2 or more kinds.

(other optional ingredients)

The resin composition of the present invention may further contain a mercapto compound, an adhesion promoter, an antioxidant, an ultraviolet absorber, and other components as necessary. They may use substances commonly used in the field of electronic materials. Further, known and commonly used additives such as a thickener such as fine powder silica, hydrotalcite, organic bentonite, and montmorillonite, a defoaming agent and/or a leveling agent such as silicone-based, fluorine-based, and polymer-based ones, a silane coupling agent, and a rust preventive may be added.

The photosensitive thermosetting resin composition of the present invention is excellent in photosensitivity, alkali developability, and further excellent in mechanical properties such as heat resistance, and can provide excellent covering properties of a coating film independent of a difference in film thickness due to a difference in height of a circuit, and therefore, the photosensitive thermosetting resin composition can be widely used in the field of printed wiring boards, for example, as a solder resist for printed wiring boards for packaging, vehicle mounting, motherboard, flexible use, and the like.

(Dry film)

The dry film of the present invention can be produced as follows.

That is, first, the resin composition of the present invention is diluted with an organic solvent to an appropriate viscosity on a carrier film (support), and the diluted resin composition is sequentially applied by a known method such as a comma coater according to a conventional method. Thereafter, the dried film having the resin layer formed on the carrier film can be obtained by drying the film at a temperature of 50 to 130 ℃ for 1 to 30 minutes. Further, the other photosensitive resin compositions may be laminated to form a multilayer structure according to the purpose. On the dry film thus formed, a protective film that can be peeled off may be further laminated for the purpose of preventing dust from adhering to the surface of the film. As the carrier film and the protective film, conventionally known plastic films can be suitably used, and the protective film is preferably smaller than the adhesion force between the resin layer and the carrier film when the protective film is peeled. The thickness of the carrier film and the protective film is not particularly limited, and is usually suitably selected within the range of 10 to 150 μm.

(printed Circuit Board and method for manufacturing the same)

The printed wiring board of the present invention is characterized by comprising a cured product formed by using the photosensitive thermosetting resin composition of the present invention or the dry film of the present invention. The photosensitive thermosetting resin composition of the invention has the following advantages: has excellent photosensitivity, alkali developability, heat resistance, mechanical properties, and excellent hiding properties of a coating film independent of the difference in height of a circuit.

The printed wiring board of the present invention is manufactured by a manufacturing method including the steps of: a step of forming a resin layer containing the photosensitive thermosetting resin composition of the present invention on a printed circuit board on which a conductor circuit is formed (resin layer forming step); a step (exposure step) of irradiating the resin layer with an active energy ray in a pattern; and a step (developing step) of forming a patterned resin layer simultaneously with the alkali development of the resin layer. After the alkali development, if necessary, further photocuring and thermosetting (post-curing step) are performed to completely cure the resin layer, whereby a highly reliable printed wiring board can be obtained.

The printed wiring board of the present invention can be manufactured by the following steps. Namely, the manufacturing method comprises the following steps: a step of forming a resin layer containing the photosensitive thermosetting resin composition of the present invention on a printed circuit board on which a conductor circuit is formed (resin layer forming step); a step (exposure step) of irradiating the resin layer with an active energy ray in a pattern; a step of heating the resin layer (heating (PEB) step) as necessary; and a step (developing step) of forming the patterned resin insulating layer by alkali development of the resin layer. After the alkali development, the resin layer can be completely cured by further photocuring and thermosetting (post-curing step), and a highly reliable printed wiring board can be obtained. In the present invention, this step is particularly preferably utilized.

Hereinafter, each step will be described in detail.

[ resin layer Forming Process ]

In this step, at least one resin layer containing the photosensitive thermosetting resin composition of the present invention is formed on a printed wiring board.

Examples of the method for forming the resin layer include a coating method and a lamination method. In the case of the coating method, the resin composition of the present invention is coated on a printed wiring board by a method such as screen printing, and dried to form a resin layer. In the case of the lamination method, first, the resin composition of the present invention is diluted with an organic solvent to adjust to an appropriate viscosity, coated on a carrier film, and dried to prepare a dry film having a resin layer. Next, the resin layer is laminated so as to be in contact with the printed wiring board by a laminator or the like to form the resin layer. The carrier film is peeled off before the developing step.

Further, another layer may be interposed between the photosensitive thermosetting resin layer of the present invention and the printed wiring board. The other layer is preferably formed of an alkali-developable photosensitive resin composition. As the alkali development type photosensitive resin composition, a known composition can be used, and for example, a known composition for a solder resist can be used. By forming a laminated structure including other layers in this manner, a cured product further excellent in impact resistance and bendability can be obtained.

[ Exposure Process ]

The process comprises the following steps: the photopolymerization initiator contained in the resin layer is activated in a negative pattern under light irradiation to cure the light-irradiated portion. In this step, the photosensitive resin component contained in the resin composition is polymerized by the radicals generated in the light irradiation section, and becomes insoluble in the developer. In the case of a composition containing a photobase generator and a photopolymerization initiator which also functions as a photobase generator, a base is generated in the light irradiation section in this step.

As the light irradiator, a direct drawing device, a light irradiator equipped with a metal halide lamp, or the like can be used. The mask for pattern-like light irradiation is a negative mask.

The active energy ray used for light irradiation is preferably laser light or scattered light having a maximum wavelength in the range of 350 to 450 nm. By setting the maximum wavelength to this range, the photopolymerization initiator can be activated efficiently. The laser light in this range may be used, and may be either a gas laser light or a solid laser light. The amount of light irradiation varies depending on the film thickness, and can be usually set to 100 to 1500mJ/cm²。

[ heating (PEB) Process ]

A heating (PEB) step may be added as necessary. In the step, in the composition containing the photobase generator and the photopolymerization initiator functioning also as the photobase generator, the thermally reactive compound reacts with the alkali generated in the light irradiation section in the light irradiation step, and the alkali development resistance of the irradiation section is improved. The heating temperature is, for example, 80 to 140 ℃. The heating time is, for example, 1 to 100 minutes.

The reaction of the resin composition in this step is, for example, a ring-opening reaction of a thermosetting cyclic ether group-containing compound by a thermal reaction, and therefore, strain and curing shrinkage can be suppressed as compared with the case where curing proceeds by a photo radical reaction. In addition, the carboxyl group of the resin composition is reduced by the reaction, and the alkali development resistance of the light-irradiated portion is greatly improved.

[ developing Process ]

In the development step, the non-irradiated portion is removed by alkali development to form a negative-type patterned insulating film, particularly a solder resist pattern.

The developing method may be a known method such as immersion. As the developer, an alkaline aqueous solution such as sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, amines, or a tetramethylammonium hydroxide aqueous solution (TMAH), or a mixture thereof can be used. In the present invention, the use of the specific polyamideimide resin is advantageous in that, for example, development can be carried out with a weakly alkaline developer solution of 0.3 to 3 mass%.

[ post-curing step ]

In this step, after the development step, the resin layer is completely thermally cured to obtain a highly reliable coating film. The heating temperature is, for example, 140 ℃ to 180 ℃. Further, light irradiation may be performed before or after post-curing.

Examples

The present invention will be described in further detail below with reference to examples and comparative examples, but the present invention is not limited to these examples and comparative examples.

(Synthesis example 1)

In a 300mL flask having four mouths and provided with a nitrogen inlet, a thermometer and a stirrer, 28.61g (0.052mol) of aliphatic diamine (product name PRIAMINE1075, manufactured by Croda Japan) derived from a dimer acid having 36 carbon atoms as a dimer diamine (a), 4.26g (0.028mol) of 3, 5-diaminobenzoic acid as a carboxyl group-containing diamine (b) and 85.8g of gamma-butyrolactone were charged at room temperature and dissolved.

Then, 30.12g (0.152mol) of cyclohexane-1, 2, 4-tricarboxylic acid anhydride (c) and 3.07g (0.016mol) of trimellitic anhydride (d) were added thereto, and the mixture was kept at room temperature for 30 minutes. 30g of toluene was further charged, the temperature was raised to 160 ℃ to remove water formed with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain an imide-containing solution.

To the imide compound-containing solution thus obtained, 14.30g (0.068mol) of trimethylhexamethylene diisocyanate as the diisocyanate compound (e) was charged, and the mixture was held at 160 ℃ for 32 hours and diluted with 21.4g of cyclohexanone to obtain a polyamideimide resin-containing solution (A-1). The obtained polyamideimide resin had a mass average molecular weight Mw of 5250, a solid content of 41.5% by mass, an acid value of 63mgKOH/g, and a dimer diamine (a) content of 40.0% by mass.

(Synthesis example 2)

In a 300mL flask having four necks, including a nitrogen inlet, a thermometer, and a stirrer, 29.49g (0.054mol) of an aliphatic diamine (manufactured by Croda Japan, product name PRIAMINE1075) derived from a dimer acid having 36 carbon atoms as a dimer diamine (a), 4.02g (0.026mol) of 3, 5-diaminobenzoic acid as a carboxyl group-containing diamine (b), and 73.5g of gamma-butyrolactone were charged at room temperature and dissolved.

Then, 31.71g (0.160mol) of cyclohexane-1, 2, 4-tricarboxylic acid anhydride (c) and 1.54g (0.008mol) of trimellitic anhydride (d) were charged, and the mixture was kept at room temperature for 30 minutes. 30g of toluene was further charged, the temperature was raised to 160 ℃ to remove water formed with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain an imide-containing solution.

To the imide compound-containing solution thus obtained were charged 6.90g (0.033mol) of trimethylhexamethylene diisocyanate and 8.61g (0.033mol) of dicyclohexylmethane diisocyanate as the diisocyanate compound (e), and the mixture was held at 160 ℃ for 32 hours and diluted with 36.8g of cyclohexanone to obtain a polyamideimide resin-containing solution (A-2). The obtained polyamideimide resin had a mass average molecular weight Mw of 5840, a solid content of 40.4% by mass, an acid value of 62mgKOH/g, and a dimer diamine (a) content of 40.1% by mass.

(Synthesis example 3)

In a 300mL flask having four necks, including a nitrogen inlet, a thermometer, and a stirrer, 29.49g (0.054mol) of an aliphatic diamine (manufactured by Croda Japan, product name PRIAMINE1075) derived from a dimer acid having 36 carbon atoms as a dimer diamine (a), 4.02g (0.026mol) of 3, 5-diaminobenzoic acid as a carboxyl group-containing diamine (b), and 75.0g of gamma-butyrolactone were charged at room temperature and dissolved.

33.29g (0.168mol) of cyclohexane-1, 2, 4-tricarboxylic anhydride (c) was then charged and the mixture was held at room temperature for 30 minutes. 30g of toluene was further charged, the temperature was raised to 160 ℃ to remove water formed with toluene, and the mixture was held for 3 hours and cooled to room temperature to obtain an imide-containing solution.

To the imide compound-containing solution thus obtained, 16.79g (0.064mol) of dicyclohexylmethane diisocyanate as the diisocyanate compound (e) was charged, and the mixture was held at 160 ℃ for 32 hours and diluted with 37.5g of cyclohexanone to obtain a polyamideimide resin-containing solution (A-3). The polyamideimide resin thus obtained had a weight average molecular weight Mw of 6430, a solid content of 41.2% by mass, an acid value of 63mgKOH/g, and a dimer diamine (a) content of 39.3% by weight.

Comparative example Synthesis example 1

In a flask equipped with a stirrer, a thermometer and a condenser, 848.8g of GBL (. gamma. -butyrolactone), 57.5g (0.23 mol) of MDI (diphenylmethane diisocyanate), 59.4g (0.225 mol) of DMBPDI (4,4 ' -diisocyanate-3, 3 ' -dimethyl-1, 1 ' -biphenyl), 67.2g (0.35 mol) of TMA (trimellitic anhydride) and 29.7g (0.15 mol) of TMA-H (cyclohexane-1, 3, 4-tricarboxylic acid-3, 4-anhydride) were charged, and while stirring, the mixture was heated to 80 ℃ with a radiant heat, and dissolved at that temperature for 1 hour to react, and further heated to 160 ℃ for 2 hours to react at that temperature for 5 hours. The reaction proceeds with the foaming of carbon dioxide gas, and the inside of the system becomes a brown transparent liquid. A solution of the polyamideimide resin (A1) having a resin solid content of 17% and a solution acid value of 5.3(KOHmg/g) and a viscosity of 7 pas at 25 ℃ was obtained (a resin composition in which the resin was dissolved in. gamma. -butyrolactone). The solid acid value of the resin was 31.2 (KOHmg/g). The weight average molecular weight of the Gel Permeation Chromatography (GPC) was 34000.

Examples 1 to 5, comparative examples 1 to 3

The materials described in examples and comparative examples were compounded according to the formulations described in the following tables, premixed in a mixer, and kneaded by a three-roll mill to prepare a photosensitive thermosetting resin composition. The values of the blending amounts in the tables represent parts by mass of the solid components unless otherwise specified.

< optimum exposure >

A circuit pattern substrate having a copper thickness of 70 μm and a polyimide thickness of 50 μm was subjected to microetching with sulfuric acid hydrogen peroxide, washed with water, dried, and then each photosensitive thermosetting resin composition was applied to the entire surface by screen printing, followed by hot air circulation at 80 ℃And drying in a drying oven for 30 minutes. Exposure was carried out for 60 seconds (30 ℃, 0.2MPa, 1 wt% Na) using an exposure apparatus (EXP-2960) equipped with a mercury short arc lamp and a stepwise exposure meter (Kodak No.2)₂CO₃Aqueous solution) was set to 7 steps as the optimum exposure amount.

< circuit coverability >

A circuit pattern substrate having a copper circuit/gap of 300 μm/300 μm, a copper circuit thickness of 70 μm, and a polyimide base material thickness of 50 μm was prepared, microetched with hydrogen peroxide sulfate, washed with water, and dried. The photosensitive resin compositions of examples and comparative examples were applied by screen printing and dried in a hot air circulation type drying oven at 80 ℃ for 30 minutes. After drying, the entire surface was exposed to light at an optimum exposure dose for each photosensitive thermosetting resin composition using an exposure apparatus (EXP-2960) equipped with a mercury short arc lamp. After the exposure, development was performed using a1 mass% sodium carbonate aqueous solution at 30 ℃ and thermal curing was performed at 150 ℃ for 60 minutes to obtain a cured coating film.

The appearance of the circuit board coated with the obtained cured coating film was confirmed, and the hiding property was evaluated by the following index.

A: the copper circuit and the edge have uniform appearance and can not see through the color of the copper.

B: the appearance unevenness due to the film thickness difference on the circuit was observed.

C: the edge portion of the circuit is transparent and looks like a disadvantage.

< resolution >

A circuit pattern substrate having a copper circuit/gap of 300 μm/300 μm, a copper circuit thickness of 70 μm, and a polyimide base material thickness of 50 μm was prepared, microetched with hydrogen peroxide sulfate, washed with water, and dried. The photosensitive resin compositions of examples and comparative examples were applied by screen printing and dried in a hot air circulation type drying oven at 80 ℃ for 30 minutes. After drying, exposure was performed using an exposure apparatus (EXP-2960) equipped with a mercury short arc lamp. The exposure pattern used was a negative mask capable of forming a line width of 100/120/150/. mu.m at the gap portion of the substrate. The exposure dose is the optimum exposure dose for irradiating each photosensitive thermosetting resin composition. After the exposure, a pattern was drawn by development with a1 mass% aqueous solution of sodium carbonate at 30 ℃ and thermally cured at 150 ℃ for 60 minutes to obtain a cured coating film.

The minimum residual line width of the cured coating film of the obtained photosensitive resin composition for a solder resist was determined by using an optical microscope adjusted to 200 times.

A: a100 μm tin bank was formed between the copper circuits.

B: a120 μm tin bank was formed between the copper circuits.

C: a150 μm tin bank was formed between the copper circuits.

< insulation reliability >

A comb-shaped circuit pattern substrate for insulation reliability evaluation having a copper circuit/gap of 100 μm/100 μm, a copper circuit thickness of 70 μm, and a polyimide base material thickness of 50 μm was prepared, microetched with hydrogen peroxide sulfate, washed with water, and dried. The photosensitive resin compositions of examples and comparative examples were applied by screen printing and dried in a hot air circulation type drying oven at 80 ℃ for 30 minutes. After drying, the entire surface was exposed to light at an optimum exposure dose for each photosensitive thermosetting resin composition using an exposure apparatus (EXP-2960) equipped with a mercury short arc lamp. After the exposure, development was performed using a1 mass% sodium carbonate aqueous solution at 30 ℃ and thermal curing was performed at 150 ℃ for 60 minutes to obtain a cured coating film.

The obtained substrate for insulation reliability evaluation was applied with a voltage of 100V under an environment of 85 ℃ and 85 RH%, and insulation reliability after 1000 hours was confirmed by the following index.

A: after 1000 hours, no migration or short circuit occurred.

B: after 1000 hours, no short circuit occurred, but migration sometimes occurred.

C: after 1000 hours a short circuit occurred.

< solder heat resistance >

A circuit pattern substrate having a copper thickness of 70 μm and a polyimide thickness of 50 μm was polished with a polishing roll, washed with water, dried, and then each photosensitive thermosetting resin composition was applied to the entire surface by screen printing and dried in a hot air circulation type drying oven at 80 ℃ for 30 minutes. After drying, pattern exposure was performed at an optimum exposure amount for each photosensitive thermosetting resin composition using an exposure apparatus (EXP-2960) equipped with a mercury short arc lamp. After the exposure, development was performed using a1 mass% sodium carbonate aqueous solution at 30 ℃ and thermal curing was performed at 150 ℃ for 60 minutes to obtain a cured coating film.

The obtained evaluation substrate was coated with rosin-based flux, immersed in a solder bath set at 260 ℃ in advance for 10 seconds, cleaned with modified alcohol, and then subjected to a tape peeling test to evaluate swelling/peeling of the solder resist layer. The criterion is as follows.

A: the dipping was repeated for 10 seconds 2 times, and peeling was not confirmed by a peeling test using a cellophane tape.

B: the sheet was immersed for 10 seconds 1 time, and peeling was not observed even in a peeling test using a cellophane tape.

C: when the immersion was carried out for 10 seconds, the solder resist layer swelled and peeled.

< bendability test (presence or absence of crack) >

A circuit pattern substrate having a polyimide thickness of 25 μm and a copper thickness of 18 μm was prepared and subjected to pretreatment using CZ-8100 manufactured by MEC. On the circuit pattern substrate, each photosensitive thermosetting resin composition was applied to the entire surface by a screen printing method, and dried in a hot air circulation type drying oven at 80 ℃ for 30 minutes. Thereafter, the resultant was dried at 90 ℃/30 minutes in a hot air circulation drying furnace to form a coating film containing the photosensitive thermosetting resin composition.

An exposure apparatus equipped with a high-pressure mercury lamp (short arc lamp) was used to expose a substrate having the coating film obtained above at a thickness of 500mJ/cm²And carrying out whole-surface exposure. Thereafter, examples 1 to 5 and comparative examples 1,2 and 3 were subjected to a PEB process at 90 ℃ for 30 minutes, and then 1 mass% Na at 30 ℃ was used₂CO₃Aqueous solution at a spray pressure of 2kg/cm²Development was carried out for 5 minutes under the conditions of (1). Thereafter, the cured product was cured in a hot air circulation drying furnace at 150 ℃ for 60 minutes to produce a substrate having a cured coating of the photosensitive thermosetting resin composition.

The obtained substrate was cut into pieces of about 50mm by about 200mm, and the bendability was evaluated by a cylindrical mandrel tester (BYK-Gardner, Inc., No. 5710). The surface coated with the resin composition was placed on the outside, and the resin composition was bent around a mandrel bar having a diameter of 2mm to evaluate the presence or absence of crack generation.

The evaluation results are shown in table 1 below.

[ Table 1]

Notes 1 to 13 in the components shown in table 1 indicate the following.

1) PAI-1: synthesis example 1 polyamideimide resin

2) PAI-2: synthesis example 2 polyamideimide resin

3) PAI-3: synthesis example 3 polyamideimide resin

4) PAI-4: comparative Synthesis example 1 polyamideimide resin

5) PCR-1170H: carboxyl group-containing modified phenol novolak type epoxy resin (manufactured by Nippon Kabushiki Kaisha) having an acid value of 64mgKOH/g and a COOH equivalent of 890

6) M-350: trimethylolpropane EO-modified triacrylate (manufactured by Toyo Synthesis Co., Ltd.)

7)6MX 75: epoxy acrylate (Doublemer 6MX75 manufactured by Double bond Co., Ltd.)

*8)828: bisphenol A epoxy resin, epoxy equivalent 190 (Mitsubishi chemical Co., Ltd.)

9) IRGACURE 907: alkylphenone photopolymerization initiator (BASF Co., Ltd.)

10) DETX-S: diethylthioxanthone (manufactured by Nippon Kagaku Co., Ltd.)

11) IRGACURE OXE 02: oxime photopolymerization initiator (BASF Co., Ltd.)

*12)C.I.Pigment Blue 15：3

*13)C.I.Pigment Yellow147

As is apparent from the evaluation results shown in Table 1 above, the resin compositions of the examples obtained by combining the components (A) PAI-1 to PAI-3 and (B) to (D) used in the resin compositions of the examples have good resolution and excellent circuit covering properties with a change in refractive index after curing.

On the other hand, comparative example 1 shows that the polyamideimide resin PAI-4 which does not satisfy the characteristics of the present invention does not have an aliphatic unit derived from a dimer acid, and is excellent in heat resistance and insulation reliability, while being inferior in circuit covering property and bendability. As is clear from comparative examples 2 and 3, the compositions using the carboxyl group-containing epoxy acrylate resin without using a specific polyamideimide resin are inferior in heat resistance and insulation reliability, and exhibit circuit hiding properties by a colorant, which is a trade-off relationship with resolution.

Claims

1. A photosensitive thermosetting resin composition, comprising:

(A) an alkali-soluble polyamideimide resin,

(B) A resin having an unsaturated double bond and a carboxyl group,

(C) A thermosetting cyclic ether group-containing compound, and

(D) a photopolymerization initiator,

X₁is a residue of aliphatic diamine (a) derived from a dimer acid having 24 to 48 carbon atoms, X₂Is a residue of an aromatic diamine (b) having a carboxyl group, and each Y is independently a cyclohexane ring or an aromatic ring.

2. The photosensitive thermosetting resin composition according to claim 1, wherein the mass average molecular weight Mw of the polyamideimide resin (a) is 20000 or less.

3. The photosensitive thermosetting resin composition according to claim 1, wherein the (D) photopolymerization initiator comprises: and also as a photopolymerization initiator functioning as a photobase generator.

4. A dry film comprising a resin layer formed from the photosensitive thermosetting resin composition according to claim 1.

5. A printed wiring board comprising a cured product formed using the photosensitive thermosetting resin composition according to any one of claims 1 to 3 or the dry film according to claim 4.