Photosensitive resin composition, dry film, cured product, and printed wiring board

Abstract

The present invention comprises: a carboxy group-containing resin having a novolac-type backbone; an oxime ester photopolymerization initiator that exhibits absorption at least at an h-line; zirconium nitride; a cesium tungsten oxide; a photopolymerizable monomer; a thermosetting resin; and 30-50 mass% of an inorganic filler other than the zirconium nitride and the cesium tungsten oxide, in terms of solid content, with respect to the total mass of the composition. In a resin layer having a film thickness of 30 μm, the minimum value of the absorbance at a wavelength of 480-780 nm and the absorbance at a wavelength of 780-1500 nm is at least 1, and the absorbance at a wavelength of 365 nm is at least 1.3.

Description

Photosensitive resin composition, dry film, cured product, and printed circuit board

[0001] This disclosure relates to a photosensitive resin composition, a dry film, a cured product, and a printed circuit board.

[0002] Solder resist is an insulating film that covers the surface layer of printed circuit boards and semiconductor packaging substrates, protecting circuit patterns and other elements. The roles of solder resist include preventing solder from adhering to unwanted areas on printed circuit boards and semiconductor packaging substrates, protecting circuit patterns from dust, heat, and moisture, and maintaining electrical insulation between circuit patterns.

[0003] Furthermore, in printed circuit boards and semiconductor package substrates on which electronic elements such as optical sensors are mounted, high light-shielding properties are required in the solder resist from the visible light range to the near-infrared region to prevent unwanted light from entering from the outside. For example, the required light-shielding properties are met by using solder resist containing a colorant with light-shielding properties such as carbon black. However, when light-shielding is enhanced using carbon black or similar materials, there is a problem in that the resolution decreases due to light absorption by the colorant. In other words, light absorption by colorants such as carbon black makes high-resolution patterning by exposure difficult, and it is difficult to expose the solder resist to its deepest parts.

[0004] Japanese Patent Publication No. 2016-148726 discloses a solder resist composition comprising a perylene-based black coloring agent and a coloring agent other than black, and the L of a film formed by the solder resist composition ＊ Value, a ＊ Value and b ＊ A technology is disclosed that ensures the value falls within a predetermined range. According to the technology disclosed in Patent Document 1, it is possible to improve resolution and the concealment of conductor wiring by using a solder resist layer.

[0005] However, photosensitive resin compositions used as solder resists, as described above, are required not only to improve resolution and light shielding properties, but also to prevent crack formation due to thermal expansion and contraction, and to exhibit excellent drying properties after being applied to substrates, printed circuit boards, etc. Therefore, in view of the above circumstances, one embodiment of the present disclosure aims to provide a photosensitive resin composition, a dry film, a cured product of a photosensitive resin composition, and a printed circuit board that exhibit excellent resolution and light shielding properties, prevent crack formation, and have excellent drying properties.

[0006] As a result of diligent research conducted by the inventors to achieve the above-mentioned objectives, we have found that by using zirconium nitride, which mainly absorbs visible light, tungsten cesium oxide, which mainly absorbs near-infrared light, and inorganic fillers other than zirconium nitride and tungsten cesium oxide, and by specifying the content of the inorganic fillers, a photosensitive resin composition can be obtained that exhibits excellent resolution and light shielding properties, prevents crack formation, and has excellent drying properties, thus completing this disclosure. This disclosure includes the following:

[0007] <1> A photosensitive resin composition comprising: a carboxyl group-containing resin having a novolac-type skeleton; an oxime ester-based photopolymerization initiator having absorption in at least the h-ray; zirconium nitride; tungsten cesium oxide; a photopolymerizable monomer; a thermosetting resin; and an inorganic filler other than the zirconium nitride and tungsten cesium oxide, in an amount of 30% to 50% by mass on a solid content basis relative to the total mass of the composition, wherein the minimum absorbance in a resin layer with a thickness of 30 μm is 1 or more at wavelengths of 480 nm to 780 nm and 780 nm to 1500 nm, and the absorbance at a wavelength of 365 nm is 1.3 or more. <2> The photosensitive resin composition according to <1>, wherein the carboxyl group-containing resin has a cresol novolac-type skeleton. <3> The photosensitive resin composition according to <1> or <2>, further comprising a photopolymerization initiator that does not have absorption in the h-ray. <4> The photosensitive resin composition according to any one of <1> to <3>, wherein the photopolymerizable monomer comprises a photopolymerizable monomer with four or more functions. <5> The photosensitive resin composition according to any one of <1> to <4>, wherein the thermosetting resin comprises at least one selected from the group consisting of epoxy resins having a phenol novolac type and epoxy resins having an alicyclic skeleton. <6> The photosensitive resin composition according to any one of <1> to <5>, wherein the inorganic filler has an average particle size (D50) of 10 nm to 2000 nm. <7> A dry film comprising a first film and a resin layer disposed on one side of the first film, wherein the resin layer is formed from the photosensitive resin composition according to any one of <1> to <6>. <8> A cured product of the resin layer of the photosensitive resin composition according to any one of <1> to <6> or the dry film according to <7>. <9> The cured product according to <8>, wherein the coefficient of linear expansion at 0°C to 50°C is 20 ppm / °C to 40 ppm / °C, and the glass transition temperature is 150°C or higher. <10> A printed circuit board comprising the cured product according to <8> or <9>.

[0008] According to one embodiment of the present disclosure, a photosensitive resin composition, a dry film, a cured product of the photosensitive resin composition, and a printed circuit board are provided that exhibit excellent resolution and light shielding properties, prevent crack formation, and have excellent drying properties.

[0009] The following describes embodiments that are examples of this disclosure. These descriptions and embodiments are illustrative and do not limit the scope of the invention. In the following embodiments, the components (including elemental steps, etc.) are not essential unless otherwise specified. The same applies to numerical values ​​and their ranges and do not limit this disclosure. For example, this disclosure allows for additions, omissions, substitutions, and changes to numbers, quantities, positions, ratios, materials, configurations, types, and order, etc., without departing from the spirit of the invention.

[0010] In this disclosure, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages in this disclosure, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range described in stages. Also, in numerical ranges described in this disclosure, the upper or lower limit of that numerical range may be replaced by the values ​​shown in the examples. In this disclosure, each component may contain multiple types of the corresponding substance. When multiple types of substances corresponding to each component exist in a composition, the content or amount of each component means the total content or amount of the multiple types of substances present in the composition, unless otherwise specified. In this disclosure, the term "layer" includes cases where the layer is formed in the entire region when the region in which the layer exists is observed, as well as cases where it is formed in only a part of the region.

[0011] In this disclosure, "(meth)acrylic acid" means either or both methacrylic acid and acrylic acid. "(meth)acrylamide" means either or both methacrylamide and acrylamide. "(meth)acrylonitrile" means either or both methacrylonitrile and acrylonitrile. "(meth)acryloyloxy group" means either or both methacryloyloxy group and acryloyloxy group.

[0012] [Photosensitive Resin Composition] The photosensitive resin composition of this disclosure comprises a carboxyl group-containing resin having a novolac-type skeleton, an oxime ester-based photopolymerization initiator having absorption in at least the h-ray, zirconium nitride, tungsten cesium oxide, a photopolymerizable monomer, a thermosetting resin, and an inorganic filler other than the zirconium nitride and tungsten cesium oxide, in an amount of 30% to 50% by mass on a solid content basis relative to the total mass of the composition, wherein the minimum absorbance in a resin layer with a thickness of 30 μm is 1 or more at wavelengths of 480 nm to 780 nm and 780 nm to 1500 nm, and the absorbance at a wavelength of 365 nm is 1.3 or more. The "resin layer with a thickness of 30 μm" means a resin layer with a thickness of 30 μm obtained by coating the photosensitive resin composition of this disclosure onto a substrate and drying it.

[0013] The photosensitive resin composition of this disclosure can form a dry film and cured product that exhibits excellent resolution and light shielding properties, prevents crack formation, and has excellent drying properties. This is presumed to be because the photosensitive resin composition of this disclosure has excellent light shielding properties over a wide wavelength range because zirconium nitride can mainly absorb visible light and tungsten cesium oxide can mainly absorb near-infrared light; it has excellent resolution because the absorbance of i-lines is high and intrafilm scattering of i-lines is suppressed by a predetermined amount of inorganic filler; it has a low coefficient of thermal expansion by incorporating a predetermined amount of inorganic filler, thereby preventing crack formation; and it has excellent drying properties because it incorporates tungsten cesium oxide which absorbs near-infrared light.

[0014] -Carboxy group-containing resin having a novolac-type skeleton- In this disclosure, the carboxyl group-containing resin having a novolac-type skeleton is at least one carboxyl group-containing resin selected from the group consisting of carboxyl group-containing resins having a cresol novolac-type skeleton and carboxyl group-containing resins having a phenol novolac-type skeleton.

[0015] In this disclosure, the carboxyl group-containing resin having a novolac-type skeleton is preferably a carboxyl group-containing resin having a cresol novolac-type skeleton. By including a carboxyl group-containing resin having a novolac-type skeleton in the photosensitive resin composition, good heat resistance can be imparted to the photosensitive resin composition. Furthermore, by including a carboxyl group-containing resin having a cresol novolac-type skeleton in the photosensitive resin composition, the resolution of the photosensitive resin composition can be improved. By including a carboxyl group-containing resin having a phenol novolac-type skeleton in the photosensitive resin composition, high sensitivity can be achieved by imparting good fluidity to the photosensitive resin composition, and excellent developability can be imparted. The carboxyl group-containing resin having a phenol novolac-type skeleton means that both carboxyl group-containing resins having a biphenol novolac-type skeleton and carboxyl group-containing resins having a biphenyl novolac-type skeleton are included. Specific examples of carboxyl group-containing resins having a novolac-type skeleton include the following compounds (which may be either oligomers or polymers).

[0016] (1) A carboxyl group-containing resin obtained by reacting a novolac-type epoxy resin with (meth)acrylic acid and adding a dibasic acid anhydride to the hydroxyl groups present in the side chain. (2) A carboxyl group-containing resin obtained by reacting a novolac-type epoxy resin with a compound having at least one alcoholic hydroxyl group and one phenolic hydroxyl group in one molecule, such as p-hydroxyphenethyl alcohol, and an unsaturated group-containing monocarboxylic acid such as (meth)acrylic acid, and then reacting the alcoholic hydroxyl group of the resulting reaction product with a polybasic acid anhydride such as maleic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride, or adipic anhydride. (3) A carboxyl group-containing photosensitive resin obtained by further adding a compound having one epoxy group and one or more (meth)acryloyl groups in one molecule to the resin of (1) or (2).

[0017] The acid value of the carboxyl group-containing resin having a novolac-type skeleton is preferably 30 mg KOH / g to 150 mg KOH / g, and more preferably 50 mg KOH / g to 120 mg KOH / g. Setting the acid value of the carboxyl group-containing resin having a novolac-type skeleton to 30 mg KOH / g or higher improves alkali developability. Furthermore, setting the acid value to 150 mg KOH / g or lower makes it easier to draw good resist patterns.

[0018] The weight-average molecular weight of a carboxyl group-containing resin having a novolac-type skeleton varies depending on the resin skeleton, but is generally preferably 2,000 to 150,000. A weight-average molecular weight of 2,000 or more can improve tack-free performance and resolution. Furthermore, a weight-average molecular weight of 150,000 or less can improve developability and storage stability. More preferably, the weight-average molecular weight of a carboxyl group-containing resin having a novolac-type skeleton is 5,000 to 100,000.

[0019] The amount of carboxyl group-containing resin having a novolac-type skeleton in the photosensitive resin composition is preferably 10% to 40% by mass, more preferably 20% to 35% by mass, on a solid content basis. By setting the amount of carboxyl group-containing resin having a novolac-type skeleton to 10% by mass or more, the coating strength can be improved. Furthermore, by setting the amount of carboxyl group-containing resin having a novolac-type skeleton to 40% by mass or less, the viscosity becomes appropriate and processability is improved.

[0020] Furthermore, the photosensitive resin composition of this disclosure may further contain a carboxyl group-containing resin that does not have a novolac-type skeleton, in addition to the carboxyl group-containing resin having a novolac-type skeleton as described above. However, in the photosensitive resin composition of this disclosure, the content of the carboxyl group-containing resin that does not have a novolac-type skeleton is preferably within a range that does not impair the effects of this disclosure, such as exhibiting excellent resolution and light shielding properties, preventing crack formation, and having excellent drying properties.

[0021] - Oxime ester-based photopolymerization initiator - The photosensitive resin composition of this disclosure includes an oxime ester-based photopolymerization initiator having absorption at least in the h-ray (405 nm) as a photopolymerization initiator. An oxime ester-based photopolymerization initiator having absorption at least in the h-ray means including an oxime ester-based photopolymerization initiator that has absorption only in the h-ray, and an oxime ester-based photopolymerization initiator that has absorption in ultraviolet light other than the h-ray, such as the g-ray (436 nm) and i-ray (365 nm), as well as the h-ray. The photopolymerization initiator used in the photosensitive resin composition of this disclosure preferably has an absorption peak in the h-ray (405 nm). The photosensitive resin composition of this disclosure can have excellent resolution by using an oxime ester-based photopolymerization initiator having absorption at least in the h-ray (405 nm).

[0022] In particular, the photosensitive resin composition of this disclosure preferably includes an oxime ester-based photopolymerization initiator having absorption in at least the h-ray and a photopolymerization initiator that does not have absorption in the h-ray. Further inclusion of a photopolymerization initiator that does not have absorption in the h-ray in the photosensitive resin composition of this disclosure results in even better resolution. Note that a photopolymerization initiator that does not have absorption in the h-ray is synonymous with a photopolymerization initiator that has absorption in the i-ray among the h-ray and i-ray. Furthermore, an oxime ester-based photopolymerization initiator having absorption in at least the h-ray can be rephrased as an oxime ester-based photopolymerization initiator that has absorption in both the h-ray and i-ray.

[0023] Examples of oxime ester-based photopolymerization initiators having absorption in at least the h-ray include Adeka Arcles NCI-831, NCI-831E, and TOE-04-A3 manufactured by Nippon Chemical Industrial Co., Ltd.

[0024] By using an oxime ester-based photopolymerization initiator that absorbs at least the h-ray, the polymerization of the carboxyl group-containing resin and the photopolymerizable monomer described above can be efficiently promoted, reducing unreacted components after exposure and curing of the photosensitive resin composition, and improving resolution. The oxime ester-based photopolymerization initiator that absorbs at least the h-ray may be used alone or in combination of two or more types.

[0025] The content of the oxime ester-based photopolymerization initiator having absorption in at least the h-ray can be 0.1 to 20 parts by mass, and preferably 1 to 10 parts by mass, per 100 parts by mass of the carboxyl group-containing resin, on a solid content basis. When the content is 1 part by mass or more, the photocurability of the photosensitive resin composition is good, the coating is less likely to peel off, and the coating properties such as chemical resistance are also good. On the other hand, when the content is 20 parts by mass or less, an outgassing effect is obtained, and furthermore, light absorption on the surface of the solder resist coating is good, and the deep curing performance is less likely to decrease.

[0026] Examples of photopolymerization initiators that do not absorb h rays include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-,2-(O-benzoyl oxime), ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime). Examples of commercially available photopolymerization initiators include Irgacure OXE01 and OXE02 from BASF Japan Ltd., Omnirad 907 from IGM Resins, and N-1919 from ADEKA Corporation.

[0027] Furthermore, the photosensitive resin composition of this disclosure may be used in combination with the oxime ester-based photopolymerization initiator having absorption in at least the h-ray, as described above, by using a photoinitiator or sensitizer. Examples of photoinitiators or sensitizers include benzoin compounds, anthraquinone compounds, thioxanthone compounds, ketal compounds, benzophenone compounds, tertiary amine compounds, and xanthone compounds. In particular, it is preferable to use thioxanthone compounds such as 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, and 4-isopropylthioxanthone. The inclusion of thioxanthone compounds can improve the deep curing properties of the photosensitive resin composition. These compounds may also be used as photopolymerization initiators, but it is preferable to use them in combination with a photopolymerization initiator. The photoinitiator and sensitizer may each be used individually or in combination of two or more.

[0028] - Zirconium Nitride - The photosensitive resin composition of this disclosure mainly contains zirconium nitride, which absorbs visible light. As zirconium nitride, commercially available products such as NITRBLACK UB-1 and NITRBLACK UB-2 manufactured by Mitsubishi Materials Electronic Chemicals, Ltd. can be used.

[0029] In the photosensitive resin composition of this disclosure, the zirconium nitride content is preferably 0.1% to 10% by mass, more preferably 0.3% to 5% by mass, and even more preferably 0.5% to 2% by mass, on a solid content basis. By setting the zirconium nitride content to 0.1% by mass or more, the visible light absorption effect is sufficiently exhibited, and a better light-shielding effect in the visible light region can be achieved. Furthermore, by setting the zirconium nitride content to 10% by mass or less, good deep curing properties can be obtained in the photosensitive resin composition.

[0030] -Tungsten Cesium Oxide- The photosensitive resin composition of this disclosure mainly contains tungsten cesium oxide, which absorbs near-infrared light. As the tungsten cesium oxide, commercially available products such as YMF-02A manufactured by Sumitomo Metal Mining Co., Ltd. can be used.

[0031] In the photosensitive resin composition of this disclosure, the content of tungsten cesium oxide is preferably 0.1% to 20% by mass, more preferably 0.5% to 10% by mass, and even more preferably 0.7% to 5% by mass, in terms of solid content. By setting the tungsten cesium oxide content to 0.1% by mass or more, the near-infrared absorption effect is sufficiently exhibited, resulting in a better light-shielding effect against near-infrared rays and excellent drying properties. Furthermore, by setting the tungsten cesium oxide content to 20% by mass or less, good resolution can be obtained.

[0032] —Inorganic Filler— The photosensitive resin composition according to the present disclosure contains an inorganic filler other than the above-mentioned zirconium nitride and cesium tungsten oxide in an amount of 30% by mass to 50% by mass in terms of solid content relative to the total mass of the composition. The inorganic filler is not particularly limited, and examples thereof include silica, crystalline silica, Neuburg siliceous earth, aluminum hydroxide, glass powder, talc, clay, magnesium carbonate, calcium carbonate, natural mica, synthetic mica, barium sulfate, barium titanate, iron oxide, non-fibrous glass, hydrotalcite, mineral wool, aluminum silicate, calcium silicate, zinc white, and the like. Among these, silica, crystalline silica, and talc are preferably used as the inorganic filler.

[0033] The content of the inorganic filler, in terms of solid content relative to the total mass of the composition, is 30% by mass to 50% by mass, preferably 35% by mass to 50% by mass, and more preferably 40% by mass to 50% by mass. When the blending amount of the inorganic filler is 30% by mass or more, the coefficient of thermal expansion of the photosensitive resin composition of the present disclosure can be kept low, and the occurrence of cracks in a cured product can be suppressed. Further, by setting the content of the inorganic filler to 50% by mass or less, light scattering caused by the inorganic filler can be suppressed, and excellent resolution can be achieved.

[0034] Further, as the inorganic filler, those obtained by introducing a photoreactive or thermoreactive functional group (reactive group) onto the surface can be used. By using such an inorganic filler, high heat resistance and adhesiveness can be further improved through reaction with a carboxy group-containing resin or a thermosetting resin.

[0035] The inorganic filler can be obtained by treating the surface of the inorganic filler with a surface treatment agent having a reactive group, for example, a coupling agent having a reactive group as an organic group.

[0036] Examples of the photoreactive group include an acryloyl group, a methacryloyl group, a vinyl group, a cyclic ether group, a cyclic thioether group, and the like. Among these, at least one of a (meth)acryloyl group and a vinyl group is preferable.

[0037] Examples of heat-reactive groups include hydroxyl groups, carboxyl groups, isocyanate groups, amino groups, imino groups, epoxy groups, oxetanyl groups, mercapto groups, methoxymethyl groups, methoxyethyl groups, ethoxymethyl groups, ethoxyethyl groups, and oxazoline groups. Among these, at least one of amino groups and epoxy groups is preferred.

[0038] As a coupling agent, a coupling agent capable of introducing the above-mentioned photoreactive or thermoreactive groups to the inorganic filler can be used. Examples of coupling agents include silane coupling agents, titanium coupling agents, zirconium coupling agents, and aluminum coupling agents. Among these, silane coupling agents are preferred. Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N-(2-aminomethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane, which can be used alone or in combination. It is preferable that these silane coupling agents are pre-immobilized on the surface of the inorganic filler by adsorption or reaction.

[0039] The average particle diameter of the inorganic filler is preferably 10 nm to 2000 nm, more preferably 20 nm to 1000 nm, and still more preferably 50 nm to 500 nm. When the average particle diameter of the inorganic filler is 10 nm to 2000 nm, the filling efficiency of the inorganic filler is improved, and an excellent balance between the strength of the cured product and the laminating property of the dry film is achieved. The average particle diameter of the inorganic filler refers to the average particle diameter (D50) of primary particles, which is a value of D50 measured by laser diffraction. As a measuring apparatus based on laser diffraction, Microtrac MT3300EXII manufactured by MicrotracBEL Corp. can be mentioned. In addition, the average particle diameter of the inorganic filler contained in the photosensitive resin composition of the present disclosure refers to a value measured for the inorganic filler as described above before the photosensitive resin composition is prepared (preliminary stirring and kneading).

[0040] -Zirconium Nitride, Cesium Tungsten Oxide- In the photosensitive resin composition of the present disclosure, the total content of zirconium nitride and cesium tungsten oxide is not particularly limited, but is preferably 0.5% by mass to 10% by mass, more preferably 0.5% by mass to 8% by mass, and still more preferably 1% by mass to 5% by mass, in terms of solid content in the photosensitive resin composition. By setting the total content of zirconium nitride and cesium tungsten oxide within this range, excellent light-shielding properties can be achieved over a wide wavelength range from visible light to near-infrared rays.

[0041] Furthermore, in the photosensitive resin composition of the present disclosure, regarding the content ratio of zirconium nitride and cesium tungsten oxide, based on mass, it is preferable that the content of cesium tungsten oxide is larger than that of zirconium nitride. The content of cesium tungsten oxide can be 1.1 times, 1.5 times, 2.0 times, 2.5 times, 3.0 times, or 3.5 times the content of zirconium nitride. By setting the content ratio of zirconium nitride and cesium tungsten oxide within this range, good resolution can be obtained.

[0042] - Photopolymerizable Monomers - The photosensitive resin compositions of this disclosure contain photopolymerizable monomers. Photopolymerizable monomers are, for example, monomers having an ethylenically unsaturated double bond. Examples of such photopolymerizable monomers include conventionally known polyester (meth)acrylates, polyether (meth)acrylates, urethane (meth)acrylates, carbonate (meth)acrylates, epoxy (meth)acrylates, and the like. Specifically, alkyl acrylates such as 2-ethylhexyl acrylate and cyclohexyl acrylate; hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate and 2-hydroxypropyl acrylate; mono- or diacrylates of alkylene oxide derivatives such as ethylene glycol, propylene glycol, diethylene glycol, and dipropylene glycol; acrylamides such as N,N-dimethylacrylamide, N-methylolacrylamide, and N,N-dimethylaminopropylacrylamide; aminoalkyl acrylates such as N,N-dimethylaminoethyl acrylate and N,N-dimethylaminopropyl acrylate; polyacrylates such as hexanediol, trimethylolpropane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, and trishydroxyethyl isocyanurate. Polyvalent acrylates derived from hydrogenic alcohols or their alkylene oxide adducts or ε-caprolactone adducts; polyvalent acrylates derived from phenols such as phenoxyacrylate and bisphenol A diacrylate or their alkylene oxide adducts; acrylates derived from glycidyl ethers such as glycerin diglycidyl ether, trimethylolpropane triglycidyl ether, and triglycidyl isocyanurate; and, not limited to the above, acrylates obtained by directly acrylateting polyols such as polyether polyols, polycarbonate diols, hydroxyl-terminated polybutadienes, and polyester polyols, or by urethane acrylates via diisocyanates, as well as melamine acrylate and at least one of each methacrylate corresponding to the acrylates can be appropriately selected and used. Such photopolymerizable monomers can also be used as reactive diluents.

[0043] In this disclosure, the photopolymerizable monomer preferably includes a photopolymerizable monomer with four or more functions. A photopolymerizable monomer with four or more functions means, for example, a photopolymerizable monomer having four or more ethylenically unsaturated double bonds in one molecule. More preferably, a photopolymerizable monomer with six or more functions is used. Examples of photopolymerizable monomers with four or more functions include ditrimethylolpropanetetra(meth)acrylate, pentaerythritoltetra(meth)acrylate, polyepoxytetra(meth)acrylate, polyestertetra(meth)acrylate, penta(meth)acrylate such as dipentaerythritol penta(meth)acrylate and tripentaerythritol penta(meth)acrylate, hexa(meth)acrylate such as dipentaerythritol hexa(meth)acrylate and tripentaerythritol hexa(meth)acrylate, hepta(meth)acrylate such as tripentaerythritol hepta(meth)acrylate, octa(meth)acrylate such as tripentaerythritol octa(meth)acrylate, four or more functional polyurethane poly(meth)acrylate, four or more functional polyepoxy poly(meth)acrylate, and four or more functional polyester poly(meth)acrylate. Furthermore, examples include modified products of these tetrafunctional or higher (meth)acrylate monomers, such as polyalkylene oxide modified adducts, polycaprolactone modified adducts, and polycarbonate modified adducts; tetrafunctional or higher polyurethane poly(meth)acrylates; tetrafunctional or higher polyepoxy poly(meth)acrylates; and tetrafunctional or higher polyester poly(meth)acrylates. These tetrafunctional or higher photopolymerizable monomers may be used individually or in combination of two or more. By including tetrafunctional or higher photopolymerizable monomers, the crosslinking density during photopolymerization of the photosensitive resin composition is increased, thereby improving the heat resistance of the photosensitive resin composition.

[0044] The content of the photopolymerizable monomer in the photosensitive resin composition can be 1 to 50 parts by mass, preferably 2 to 30 parts by mass, and more preferably 5 to 10 parts by mass, based on solid content, per 100 parts by mass of the carboxyl group-containing resin. When the content of the photopolymerizable monomer is 1 part by mass or more, the photocurability is good, and pattern formation is easy during alkaline development after irradiation with active energy rays. On the other hand, when the content of the photopolymerizable monomer is 50 parts by mass or less, halation is less likely to occur and good resolution can be obtained.

[0045] -Thermosetting Resin- The photosensitive resin composition of this disclosure includes a thermosetting resin. By including a thermosetting resin in the photosensitive resin composition, the cured product formed using the photosensitive resin composition can have a low coefficient of thermal expansion, thereby preventing the occurrence of cracks. Any known thermosetting resin can be used. For example, known thermosetting resins such as melamine resin, benzoguanamine resin, melamine derivatives, amino resins such as benzoguanamine derivatives, isocyanate compounds, blocked isocyanate compounds, cyclocarbonate compounds, epoxy compounds, oxetane compounds, episulfide resins, bismaleimide, and carbodiimide resins can be used. Of these, thermosetting resins having multiple cyclic ether groups or cyclic thioether groups (hereinafter abbreviated as cyclic (thio) ether groups) in the molecule are particularly preferred.

[0046] The thermosetting resins having multiple cyclic (thio) ether groups in the molecule described above are compounds having multiple 3, 4, or 5-membered cyclic (thio) ether groups in the molecule. Examples include compounds having multiple epoxy groups in the molecule, i.e., polyfunctional epoxy compounds; compounds having multiple oxetanyl groups in the molecule, i.e., polyfunctional oxetane compounds; and compounds having multiple thio ether groups in the molecule, i.e., episulfide resins.

[0047] Polyfunctional epoxy compounds include biphenyl-type epoxy resins (biphenyl skeleton-containing epoxy resins); epoxidized vegetable oils; bisphenol A-type epoxy resins; bisphenol F-type epoxy resins; hydroquinone-type epoxy resins; bisphenol-type epoxy resins; thioether-type epoxy resins; brominated epoxy resins; novolac-type epoxy resins; biphenol novolac-type epoxy resins; hydrogenated bisphenol A-type epoxy resins; glycidylamine-type epoxy resins; hydantoin-type epoxy resins; alicyclic epoxy resins; trihydroxyphenylmethane-type epoxy resins; bixylenol-type or biphenol-type epoxy resins. Examples of epoxy resins include, but are not limited to, epoxy resins or mixtures thereof; bisphenol S type epoxy resins; bisphenol A novolac type epoxy resins; tetraphenyloleethane type epoxy resins; heterocyclic epoxy resins; diglycidyl phthalate resins; tetraglycidyl xylenolethane resins; naphthalene group-containing epoxy resins; epoxy resins having a dicyclopentadiene skeleton; glycidyl methacrylate copolymer epoxy resins; copolymer epoxy resins of cyclohexylmaleimide and glycidyl methacrylate; epoxy-modified polybutadiene rubber derivatives; and CTBN-modified epoxy resins.

[0048] Examples of polyfunctional 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, and (3-ethyl-3-oxetanyl)methyl acrylate. Examples include polyfunctional oxetanes such as relates, (3-methyl-3-oxetanyl)methyl methacrylate, (3-ethyl-3-oxetanyl)methyl methacrylate, and their oligomers or copolymers, as well as ethers of oxetane alcohols with resins having hydroxyl groups such as novolac resins, poly(p-hydroxystyrene), cardo-type bisphenols, calixarenes, calixresorcinarenes, or silsesquioxane. Other examples include copolymers of unsaturated monomers having an oxetane ring with alkyl (meth)acrylates.

[0049] Examples of compounds having multiple cyclic thioether groups in their molecules include bisphenol A type episulfide resins. Furthermore, episulfide resins obtained by replacing the oxygen atoms in the epoxy groups of novolac type epoxy resins with sulfur atoms using a similar synthesis method can also be used.

[0050] Examples of amino resins such as melamine derivatives and benzoguanamine derivatives include methylolmelamine compounds, methylolbenzoguanamine compounds, methylol glycol uryl compounds, and methylol urea compounds.

[0051] Polyisocyanate compounds can be incorporated as isocyanate compounds. Examples of polyisocyanate compounds include aromatic polyisocyanates 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 dimer; aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, methylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-methylenebis(cyclohexyl isocyanate), and isophorone diisocyanate; alicyclic polyisocyanates such as bicycloheptane triisocyanate; and adducts, biuret compounds, and isocyanurates of the isocyanate compounds mentioned above.

[0052] As the blocked isocyanate compound, the addition reaction product of an isocyanate compound and an isocyanate blocking agent can be used. Examples of isocyanate compounds that can react with an isocyanate blocking agent include the polyisocyanate compounds mentioned above. Examples of isocyanate blocking agents include phenol-based blocking agents, lactam-based blocking agents, activated methylene-based blocking agents, alcohol-based blocking agents, oxime-based blocking agents, mercaptan-based blocking agents, acid amide-based blocking agents, imide-based blocking agents, amine-based blocking agents, imidazole-based blocking agents, and imine-based blocking agents.

[0053] Furthermore, among epoxy resins, epoxy resins having an alicyclic skeleton can be used as the thermosetting resin in order to minimize coloration of the cured product so as not to inhibit luminescence. The epoxy resin having an alicyclic skeleton may be a hydrogenated epoxy resin of an epoxy resin having an aromatic ring, such as bisphenol A type epoxy resin. Examples of alicyclic skeletons include cyclopentane rings, dicyclopentadiene rings, and cyclohexane rings. Examples of epoxy resins having an alicyclic skeleton include ST-6100 manufactured by Nippon Steel Chemical & Material Co., Ltd. and YX8000 manufactured by Mitsubishi Chemical Corporation.

[0054] In particular, in the photosensitive resin composition of this disclosure, it is preferable to use at least one thermosetting resin selected from the group consisting of epoxy resins having a phenol novolac type and epoxy resins having an alicyclic skeleton, among the thermosetting resins described above. By using at least one thermosetting resin selected from the group consisting of epoxy resins having a phenol novolac type and epoxy resins having an alicyclic skeleton, the cured product formed using the photosensitive resin composition of this disclosure can have a low coefficient of thermal expansion, thereby preventing the occurrence of cracks.

[0055] The thermosetting resin content is preferably such that the number of functional groups of the thermosetting resin reacting with the carboxyl group-containing resin is 0.6 to 2.5 equivalents, more preferably 0.8 to 2.0 equivalents, relative to the carboxyl group equivalents contained in the carboxyl group-containing resin. Furthermore, the thermosetting resin content in the photosensitive resin composition can be 30 to 60 parts by mass, preferably 35 to 55 parts by mass, and more preferably 40 to 50 parts by mass, per 100 parts by mass of the carboxyl group-containing resin, on a solid content basis. When the thermosetting resin content is 30 parts by mass or more, the cured product formed from the photosensitive resin composition can exhibit excellent heat resistance. When the thermosetting resin content is 60 parts by mass or less, good resolution can be obtained.

[0056] - Absorbance Characteristics of the Resin Layer - A resin layer with a thickness of 30 μm prepared using the photosensitive resin composition of this disclosure has the following characteristics: the minimum absorbance values ​​for wavelengths of 480 nm to 780 nm and 780 nm to 1500 nm are 1 or greater, and the absorbance at 365 nm is 1.3 or greater. The resin layer can be prepared by coating the photosensitive resin composition having the above composition onto a suitable substrate and then drying it. The absorbance of the resin layer can be measured using a spectrophotometer. The photosensitive resin composition having the above composition may be dissolved in an organic solvent before forming the resin layer, if necessary.

[0057] As organic solvents, for example, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene, and tetramethylbenzene; glycol ethers such as cellosolve, methyl cellosolve, butyl cellosolve, carbitol, methyl carbitol, butyl carbitol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol diethyl ether, diethylene glycol monomethyl ether acetate, and tripropylene glycol monomethyl ether; esters such as ethyl acetate, butyl acetate, butyl lactate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, and propylene carbonate; aliphatic hydrocarbons such as octane and decane; and petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha can be used. Organic solvents may be used individually or in combination of two or more types.

[0058] The volatilization drying of organic solvents can be carried out using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, or the like.

[0059] In a resin layer with a thickness of 30 μm, the minimum absorbance values ​​for wavelengths of 480 nm to 780 nm and 780 nm to 1500 nm are 1 or greater, and the absorbance at 365 nm is 1.3 or greater, resulting in excellent resolution. Resolution can be evaluated as described in the examples. That is, a dry film formed on a substrate using the photosensitive resin composition of this disclosure is exposed to an aperture pattern of predetermined dimensions, and the resolution can be evaluated based on the dimensions of the aperture formed after development. In this case, if the dimensions of the exposed surface match the dimensions of the aperture pattern and the dimensions of the substrate side are larger than the dimensions of the aperture pattern in the aperture formed after development, this is called undercut. Also, if the dimensions of the substrate side match the dimensions of the aperture pattern and the dimensions of the exposed surface are smaller than the dimensions of the aperture pattern in the aperture formed after development, this is called halation. Excellent resolution means that neither undercut nor halation occurs and the aperture can be formed to the dimensions of the aperture pattern, or even if undercut or halation occurs, the difference from the dimensions of the aperture pattern is small.

[0060] In particular, when using the photosensitive resin composition of this disclosure, for example, an opening formed by exposing an aperture pattern with dimensions of 150 μm can be made to have an undercut of, for example, 3 μm or less, preferably 2 μm or less.

[0061] -Applications- The photosensitive resin composition of this disclosure is useful for forming pattern layers as permanent coatings for printed circuit boards, such as solder resists, coverlays, and interlayer insulating layers, and is particularly useful for forming solder resists. Furthermore, the photosensitive resin composition of this disclosure can be used not only for forming pattern layers of cured films, but also for applications that do not involve forming pattern layers, such as molding applications (encapsulation applications).

[0062] [Dry Film] The dry film of this disclosure comprises a first film and a resin layer disposed on one side of the first film, wherein the resin layer is formed from the photosensitive resin composition of this disclosure described above. The dry film of this disclosure may also comprise a second film peelably laminated on the surface of the resin layer.

[0063] -Resin Layer- In the dry film of this disclosure, the resin layer is formed by applying and drying a photosensitive resin composition. The thickness of the resin layer is not particularly limited and can be appropriately selected depending on the purpose. Specifically, to produce the resin layer, the photosensitive resin composition of this disclosure is diluted with the above-mentioned organic solvent as needed to adjust to an appropriate viscosity, and then applied to the first film to a uniform thickness using a comma coater, blade coater, lip coater, rod coater, squeeze coater, reverse coater, transfer roll coater, gravure coater, spray coater, die coater, bar coater, kiss coater, curtain coater, roll coater, knife coater, fountain coater, etc., and usually dried at a temperature of 50°C to 130°C for 1 to 30 minutes. There are no particular limitations on the coated film thickness, but generally, the film thickness after drying is appropriately selected in the range of 1 μm to 150 μm, preferably 10 μm to 60 μm.

[0064] Since the photosensitive resin composition of this disclosure has excellent drying properties, the dry film prepared as described above can exhibit good tackiness. The tackiness of the dry film can be determined by touching the surface of the resin layer after drying the wet coating at 80°C for 10 minutes, as described in the examples, and checking whether a fingerprint remains on the surface.

[0065] -First Film- The first film (hereinafter also referred to as the "support film") has the role of supporting the resin layer of the dry film, and is coated with the photosensitive resin composition when forming the aforementioned resin layer. In this disclosure, when laminating the dry film so that the resin layer side is in contact with the substrate, it refers to a film that is at least adhered to the resin layer. The first film may be peeled off from the resin layer in a process after lamination. In particular, in this disclosure, it is preferable to peel off the first film from the resin layer in a process after exposure.

[0066] The first film can be any known film without particular limitations, and for example, films made of thermoplastic resins such as polyester films (polyethylene terephthalate, polyethylene naphthalate, etc.), polyimide films, polyamide-imide films, polypropylene films, and polystyrene films can be suitably used. Among these, polyester films are preferred from the viewpoint of heat resistance, mechanical strength, and ease of handling. Laminates of these films can also be used as the first film.

[0067] Furthermore, from the viewpoint of improving mechanical strength, the thermoplastic resin film described above is preferably a film stretched in one or two axes.

[0068] The thickness of the first film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0069] -Second Film- The second film (also called a "protective film" or "cover film") can be peelably laminated onto the surface of the resin layer for purposes such as preventing dust from adhering to the surface of the resin layer. The second film has any configuration in the dry film of this disclosure. The second film is peeled off from the resin layer before lamination when the dry film of this disclosure is laminated onto a substrate so that the resin layer side is in contact with it. As the second film, for example, polyethylene film, polytetrafluoroethylene film, polypropylene film, surface-treated paper, etc., should be such that the adhesive force between the resin layer and the second film is less than the adhesive force between the resin layer and the first film when the second film is peeled off.

[0070] The thickness of the second film is not particularly limited, but can be, for example, 10 μm to 150 μm.

[0071] [Cured Product] The cured product of this disclosure is obtained by curing the resin layer of the photosensitive resin composition or dry film of this disclosure described above. The cured product of this disclosure can be suitably used in printed circuit boards, electronic components, etc. The cured product of this disclosure has excellent light shielding properties over a wide wavelength range from visible light to near-infrared light, a low coefficient of thermal expansion, and a high glass transition temperature, which prevents crack formation. Furthermore, it has excellent curability in the deeper parts in the film thickness direction, resulting in excellent insulation reliability. In the cured product of this disclosure, it is preferable that the coefficient of linear expansion (CTE) at 0°C to 50°C is 20 ppm / °C to 40 ppm / °C, and the glass transition temperature (Tg) is 150°C or higher. The glass transition temperature is the value measured using a thermomechanical analyzer.

[0072] In the cured product of this disclosure, a CTE of 20 ppm / °C or higher is preferable from the viewpoint of improving resolution and the tensile elongation of the cured coating. Furthermore, in the cured product of this disclosure, a CTE of 40 ppm / °C or lower is preferable from the viewpoint of crack resistance and reduction of substrate warping. In particular, in the cured product of this disclosure, a CTE of 22 ppm / °C to 38 ppm / °C is preferable. Furthermore, in the cured product of this disclosure, a Tg of 150°C or higher is preferable from the viewpoint of insulation reliability and crack resistance.

[0073] Furthermore, to produce a cured product on a substrate such as a printed circuit board using the dry film of this disclosure, the second film is peeled off from the dry film, the exposed resin layer of the dry film is placed on the substrate, and the layers are bonded together using a laminator or the like to form a resin layer on the substrate. Then, the resin layer is exposed to light, developed, and heat-cured to form a cured product. The first film may be peeled off either before or after exposure.

[0074] [Printed Wiring Boards] The printed wiring boards of this disclosure have a cured product obtained from the photosensitive resin composition of this disclosure or the resin layer of the dry film of this disclosure. As a method for manufacturing the printed wiring boards of this disclosure, for example, the photosensitive resin composition of this disclosure is adjusted to a viscosity suitable for the coating method using the above-mentioned organic solvent, and applied to a substrate by methods such as dip coating, flow coating, roll coating, bar coating, screen printing, curtain coating, inkjet, dispensing, and spray coating. Then, the organic solvent contained in the composition is evaporated and dried (pre-dried) at a temperature of 60°C to 100°C to form a resin layer with excellent tackiness. In the case of dry films, the resin layer is bonded to the substrate using a laminator or the like so that the resin layer is in contact with the substrate, thereby forming a resin layer on the substrate.

[0075] Examples of the above-mentioned substrates include printed circuit boards and flexible printed circuit boards with circuits pre-formed using copper, etc., copper-clad laminates using paper phenol, paper epoxy, glass cloth epoxy, glass polyimide, glass cloth / nonwoven fabric epoxy, glass cloth / paper epoxy, synthetic fiber epoxy, fluororesin / polyethylene / polyphenylene ether, polyphenylene oxide / cyanate, etc., metal substrates, glass substrates, ceramic substrates, wafers, etc. In this disclosure, films such as polyimide film, polyethylene terephthalate film, and polyethylene naphthalate film can also be used as substrates.

[0076] The dry film is preferably laminated onto the substrate under pressure and heat using a vacuum laminator or the like. By using such a vacuum laminator, even if the circuit-formed substrate has irregularities on its surface, the dry film adheres closely to the circuit board, preventing the inclusion of air bubbles and improving the ability to fill in depressions on the substrate surface. The pressure is preferably around 0.1 MPa to 2.0 MPa, and the heating is preferably between 40°C and 120°C.

[0077] Volatilization drying after coating the photosensitive resin composition of this disclosure can be performed using a hot air circulation drying oven, an IR oven, a hot plate, a convection oven, etc. (a method in which hot air in the dryer is brought into countercurrent contact with the support using a heat source equipped with a steam-heated air heating method, and a method in which hot air is blown onto the support from a nozzle).

[0078] After forming a resin layer on a substrate, it is selectively exposed to active energy rays through a photomask with a predetermined pattern, and the unexposed areas are developed with a dilute alkaline aqueous solution (for example, a 0.3% to 3% sodium carbonate aqueous solution) to form a pattern on the cured product. In the case of a dry film, after exposure, the first film is peeled off from the dry film and developed to form a patterned cured product on the substrate. However, within the limits that do not impair the properties, the first film may be peeled off from the dry film before exposure, and the exposed resin layer may be exposed and developed.

[0079] The exposure machine used for the above-mentioned active energy ray irradiation can be any device equipped with a high-pressure mercury lamp, ultra-high-pressure mercury lamp, metal halide lamp, mercury short-arc lamp, etc., that irradiates ultraviolet light in the range of 350 to 450 nm. Furthermore, a direct imaging device (for example, a laser direct imaging device that directly draws images with a laser using CAD data from a computer) can also be used. The lamp light source or laser light source of the direct imaging device can have a maximum wavelength in the range of 350 nm to 450 nm. The exposure amount for image formation varies depending on the film thickness, etc., but is generally 10 mJ / cm². ２ ~1000mJ / cm ２ Preferably 20 mJ / cm ２ ~800 mJ / cm ２ It can be within the range of

[0080] The above-mentioned development method can be the dipping method, shower method, spray method, brush method, etc., and alkaline aqueous solutions such as potassium hydroxide, sodium hydroxide, sodium carbonate, potassium carbonate, sodium phosphate, sodium silicate, ammonia, and amines can be used as the developing solution.

[0081] Next, the patterned cured product can be cured by active energy ray irradiation and heat curing to form a cured product. The active energy ray irradiation can be performed in the same manner as the above-described exposure, but it is preferably performed under conditions stronger than the irradiation energy during exposure. For example, 500 mJ / cm ２ to 3000 mJ / cm ２ can be used. Further, heat curing can be performed under heating conditions of 100°C to 200°C for about 20 minutes to 90 minutes. This main curing is preferably performed by heat curing after photocuring. By performing photocuring first, the flow of the resin is suppressed even during heat curing.

[0082] Hereinafter, the present disclosure will be described in more detail by way of examples, but the technical scope of the present disclosure is not limited to the following examples.

[0083] [Preparation of Photosensitive Resin Composition] Various components shown in Table 1 below were blended in the proportions (parts by mass) shown in Table 1 below, preliminarily stirred with a stirrer, and then kneaded with a bead mill to prepare a photosensitive resin composition. The unit of the numerical values in the column for each component is "parts by mass", except for the column of inorganic filler content (mass%).

[0084]

[0085] In Table 1, the blending amount of each component is a value in terms of solid content. The details of each component in Table 1 are as follows.

[0086] Synthesis Example 1: Synthesis of carboxy group-containing resin 1 119.4 g of a novolac-type cresol resin (manufactured by Aica Kogyo Co., Ltd., trade name "Shounol CRG951", OH equivalent: 119.4), 1.19 g of potassium hydroxide, and 119.4 g of toluene were charged into an autoclave equipped with a thermometer, a nitrogen introduction device, an alkylene oxide introduction device, and a stirrer. The inside of the system was replaced with nitrogen while stirring, and the temperature was increased by heating. Next, 63.8 g of propylene oxide was gradually added dropwise, and the reaction was carried out at 125°C to 132°C, 0 kg / cm ２ to 4.8 kg / cm ２The mixture was reacted for 16 hours. After cooling to room temperature, 1.56 g of 89% phosphoric acid was added to the reaction solution and mixed to neutralize the potassium hydroxide, yielding a propylene oxide reaction solution of novolac-type cresol resin with a non-volatile content of 62.1% and a hydroxyl value of 182.2 g / eq. This solution had an average of 1.08 moles of alkylene oxide added per equivalent of phenolic hydroxyl groups. Next, 293.0 g of the obtained alkylene oxide reaction solution of novolac-type cresol resin, 43.2 g of acrylic acid, 11.53 g of methanesulfonic acid, 0.18 g of methylhydroquinone, and 252.9 g of toluene were charged into a reactor equipped with a stirrer, thermometer, and air blowing tube, and the mixture was reacted at 110°C for 12 hours while blowing air at a rate of 10 ml / min and stirring. 12.6 g of water was distilled off as an azeotropic mixture with toluene. The reaction solution was then cooled to room temperature, neutralized with 35.35 g of a 15% by mass sodium hydroxide aqueous solution, and then washed with water. Toluene was then removed by distillation using an evaporator while substituting it with 118.1 g of diethylene glycol monoethyl ether acetate to obtain a novolac-type acrylate resin solution. Next, 332.5 g of the obtained novolac-type acrylate resin solution and 1.22 g of triphenylphosphine were charged into a reactor equipped with a stirrer, thermometer, and air blowing tube. Air was blown in at a rate of 10 ml / min, and while stirring, 60.8 g of tetrahydrophthalic anhydride was gradually added, and the reaction was carried out at 95°C to 101°C for 6 hours. In this way, a resin solution of carboxyl group-containing photosensitive resin 1 with a solids acid value of 88 mg KOH / g, solids content of 71% by mass, and weight-average molecular weight of 2,000 was obtained.

[0087] Synthesis Example 2: Synthesis of Carboxygroup-Containing Resin 2 In a flask equipped with a thermometer, stirrer, and reflux condenser, 119 parts by mass of diethylene glycol monomethyl ether acetate was added, and 188 parts by mass of phenol novolac type epoxy resin "EPICLON N-775" (manufactured by DIC Corporation, softening point 74°C, epoxy equivalent: 188 g / eq.) was dissolved. After adding 0.8 parts by mass of dibutylhydroxytoluene and 0.1 parts by mass of methoquinone, 50 parts by mass of acrylic acid, 40 parts by mass of dimethylolpropionic acid, and 1.4 parts by mass of triphenylphosphine were added, and the reaction was carried out at 120°C for 10 hours while blowing in air. Next, 71 parts by mass of diethylene glycol monomethyl ether acetate and 75 parts by mass of tetrahydrophthalic anhydride were added, and the reaction was carried out at 110°C for 3 hours. In this way, carboxygroup-containing resin 2 with a solids acid value of 80 mg KOH / g and a solids content of 65% by mass was obtained.

[0088] Synthesis Example 3: Synthesis of Carboxyloid-Containing Resin 3 A flask equipped with a thermometer, stirrer, dropping funnel, and reflux condenser was heated to 110°C with 400.0 g of dipropylene glycol monomethyl ether as a solvent. A mixture of 172.0 g of methacrylic acid, 100.0 g of methyl methacrylate, 114.0 g of ethyl methacrylate, 244.0 g of dipropylene glycol monomethyl ether, and 7.8 g of t-butyl peroxy-2-ethylhexanoate (Perbutyl O, manufactured by NOF Corporation) as a polymerization catalyst was added dropwise over 3 hours. The mixture was then stirred at 110°C for another 3 hours to deactivate the polymerization catalyst and obtain a copolymer resin solution. After cooling this resin solution, 158.0 g of glycidyl methacrylate, 6.0 g of triphenylphosphine, and 1.5 g of hydroquinone monomethyl ether were added, and the mixture was heated to 100°C and stirred to carry out the ring-opening addition reaction of epoxy. In this way, a resin solution of carboxyl group-containing photosensitive resin 3 with a solid content acid value of 91 mg KOH / g, a solid content of 50% by mass, and a weight-average molecular weight of 29,000 was obtained.

[0089] Carboxyloid-containing resin 1: Carboxyloid-containing resin having a cresol novolac-type skeleton synthesized in Synthesis Example 1 above Carboxyloid-containing resin 2: Carboxyloid-containing resin having a phenol novolac-type skeleton synthesized in Synthesis Example 2 above Carboxyloid-containing resin 3: Carboxyloid-containing resin synthesized in Synthesis Example 3 above Photopolymerization initiator 1: Oxime ester-based photopolymerization initiator that does not absorb h rays, manufactured by BASF Japan Ltd., Irgacure OXE02 Photopolymerization initiator 2: Oxime ester-based photopolymerization initiator that absorbs h rays and i rays, manufactured by Nippon Chemical Industries, Ltd., TOE-04-A3 Photopolymerization initiator 3: α-aminoalkylphenone-based photopolymerization initiator, manufactured by IGM Resins, Omnirad 907 Sensitizer: 2,4-diethylthioxanthone, manufactured by Nippon Kayaku Co., Ltd., DETX-S Visible light absorber 1: Zirconium nitride, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., NITRBLACK UB-2 dispersion Visible light absorber 2: Titanium black, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., UF-8 Visible light absorber 3: Carbon black, manufactured by Mitsubishi Chemical Corporation, MA-100 Near-infrared absorber: Tungsten cesium oxide, manufactured by Sumitomo Metal Mining Co., Ltd., YMF-02A Photopolymerizable monomer 1: Dipentaerythritol hexaacrylate, manufactured by Sanyo Chemical Industries, Ltd., Neomer DA600 Photopolymerizable monomer 2: Tricyclodecanedimethanol diacrylate, manufactured by Shin Nakamura Chemical Industry Co., Ltd., NK Ester A-DCP Thermosetting resin 1: Phenol novolac type epoxy resin, manufactured by DIC Corporation, N-740 Thermosetting resin 2: Bisphenol A novolac type epoxy resin, manufactured by DIC Corporation, N-870 Thermosetting resin 3: Bisphenol F epoxy resin, manufactured by Nippon Steel Chemical & Material Co., Ltd., YDF-170. Inorganic filler: Silica, manufactured by Admatex Co., Ltd., SO-C2.

[0090] [Preparation of Dry Film] The photosensitive resin compositions prepared above were each applied to a 25 μm polyester film (hereinafter referred to as PET film) using an applicator, and dried at 80°C for 10 minutes to produce a dry film having a resin layer with a thickness of 30 μm.

[0091] [Absorbance Measurement] A dry film with a resin layer thickness of 30 μm, prepared in the above [Dry Film Preparation] procedure, was laminated onto a glass substrate, and the PET film was peeled off. Subsequently, the absorbance at 480 nm to 780 nm, 780 nm to 1500 nm, and 365 nm was measured using a V-670 spectrophotometer manufactured by JASCO Corporation.

[0092] [Measurement of Coefficient of Linear Expansion (CTE) and Glass Transition Temperature (Tg)] A dry film with a resin layer thickness of 30 μm, prepared in the above [Preparation of Dry Film], was laminated onto a substrate having a low-profile 35 μm copper foil. The entire surface was exposed using an HMW680GW (metal halide lamp, scattered light) manufactured by Oak Manufacturing Co., Ltd., at an exposure level that yielded 11 steps on a step tablet (41 steps). After peeling off the PET film, it was developed at 30°C, 0.2 MPa, and 1.0 mass% sodium carbonate aqueous solution for 60 seconds, and then further exposed with an integrated exposure of 1000 mJ / cm². ２ The sample was cured by irradiating it with ultraviolet light and heating it at 160°C for 1 hour. Using the obtained evaluation substrate, the cured film was peeled off from the copper foil, and a sample was cut out to obtain a measurement size (3 mm x 10 mm). The coefficient of linear expansion (CTE) and glass transition temperature (Tg) of the sample were measured using a TMA6100 manufactured by Hitachi High-Tech Science Corporation. The measurement conditions were a test load of 5 g, and the sample was heated from room temperature at a heating rate of 10°C / min, repeated twice, to obtain the coefficient of linear expansion (CTE(α1)) less than Tg at the second heating.

[0093] [Resolution Evaluation] A dry film with a resin layer thickness of 30 μm, prepared in the above [Dry Film Preparation], was laminated onto the copper of a copper-clad laminate that had been chemically polished with an etching rate of 1 μm using an abrasive (MEC Corporation, CZ-8101B). The film was exposed using a DI exposure machine (short arc lamp) at an exposure level that yielded 11 steps on a step tablet (41 steps) to create an aperture pattern with a diameter of 150 μm. The PET film was peeled off and developed at 30°C, 0.2 MPa, and 1.0 mass% sodium carbonate aqueous solution for 60 seconds. The aperture dimensions of the exposed surface and the copper-clad laminate side at the formed aperture diameter were measured, and the value of [Aperture Dimension on Copper-Clad Laminate Side (μm)] - [Aperture Dimension on Exposed Surface (μm)] was calculated. In this example, in the resolution evaluation, a smaller value calculated by the above formula indicates better resolution, and a value of 3 μm or less was considered acceptable.

[0094] [Light-shielding performance evaluation] The transmittance was calculated using the absorbance values ​​from 480 nm to 780 nm and from 780 nm to 1500 nm measured in the [absorbance measurement] described above. Light-shielding performance was evaluated as excellent if the maximum value of both the transmittance calculated from the absorbance from 480 nm to 780 nm and the transmittance calculated from the absorbance from 780 nm to 1500 nm was 10% or less.

[0095] [Insulation Reliability Evaluation] A dry film with a resin layer thickness of 30 μm, prepared in the above [Dry Film Preparation] section, was laminated onto a pattern with a line width / spacing (L / S) of 30 μm / 30 μm, and the resulting cured material was used for evaluation. A Highly Accelerated Street Test (HAST) was performed on this evaluation cured material using SIPOS-TEG SI0601 under conditions of 85% humidity and 130°C, by applying a voltage of 5V. Under the above conditions, the change in the insulation properties of the evaluation cured material was measured, and the insulation reliability was evaluated according to the following criteria. The results are shown in Table 2.

[0096] A: 1 x 10⁻¹⁰ hours after the start of the exam ８ B: Maintained a resistance value of Ω or more. 1 × 10⁻¹⁶ hours between 150 and 200 hours from the start of the test. ８C, which maintained a resistance value of Ω or more: 1 × 10⁻¹⁶ hours between 100 and 150 hours from the start of the test. ８ D, which maintained a resistance value of Ω or more: 1 × 10⁻¹⁶ in less than 100 hours from the start of the test. ８ It did not maintain a resistance value of ohms or more.

[0097] [Crack Resistance Evaluation] A BT substrate with a copper line pattern of 35 μm width and 2 mm width, chemically polished with an etching rate of 1 μm using an abrasive (MEC Corporation, CZ-8101B), was laminated with a dry film with a resin layer thickness of 30 μm, prepared in the above [Dry Film Preparation] section. This was then exposed using a DI exposure machine (short arc lamp) with an exposure amount that yielded 11 steps on a step tablet (41 steps) to create an aperture pattern. The PET film was peeled off and developed at 30°C, 0.2 MPa, and 1.0 mass% sodium carbonate aqueous solution for 60 seconds, and then the integrated exposure amount was increased to 1000 mJ / cm². ２ An evaluation substrate was fabricated by irradiating it with ultraviolet light and then curing it by heating it at 160°C for 1 hour, forming a 3 mm square resist pattern on the copper line. This substrate was placed in a thermal cycle machine that cycles between -40°C and 150°C, and a Thermal Cycle Test (TCT) was performed. The number of cycles at which corner cracks occurred was then counted.

[0098] A: Corner crack occurs after 300 cycles or more. B: Corner crack occurs between 200 and 300 cycles. C: Corner crack occurs between 100 and 200 cycles. D: Corner crack occurs in less than 100 cycles.

[0099] [Drying Performance Evaluation] Dry films with a resin layer thickness of 75 μm were prepared in the same manner as described in [Preparation of Dry Film] above, and drying performance was evaluated by checking the tackiness. Tackiness was judged by touching the wet coating film with a finger after drying it at 80°C for 10 minutes, and checking whether a finger mark remained on the surface of the coating film. If no finger mark remained on the surface of the coating film after touching it, it was classified as A, and if a finger mark remained on the surface of the coating film after touching it, it was classified as B.

[0100] [Measurement and Evaluation Results] Table 2 summarizes the results of measuring the composition, visible light absorbance (480 nm to 780 nm), near-infrared absorbance (780 nm to 1500 nm), ultraviolet absorbance (365 nm), CTEα1, and glass transition temperature of Examples 1 to 5 and Comparative Examples 1 to 8. Note that the units of the numerical values ​​in each component column are "parts by mass," except for the column for inorganic filler content (mass%).

[0101]

[0102] Table 3 shows the composition, resolution evaluation, light shielding evaluation, insulation reliability evaluation, crack resistance evaluation, and drying performance evaluation results for Examples 1-5 and Comparative Examples 1-8. Note that the units of the numerical values ​​in each component column are "parts by mass," except for the inorganic filler content (mass%) column.

[0103]

[0104] As shown in Tables 2 and 3, the photosensitive resin compositions of Examples 1 to 5 were found to be superior to Comparative Examples 1 to 8 in all aspects, including resolution, light shielding, crack resistance, and drying properties.

[0105] The disclosure of Japanese Patent Application No. 2025-054371, filed on 27 March 2025, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted to be incorporated by reference.

Claims

1. A photosensitive resin composition comprising: a carboxyl group-containing resin having a novolac-type skeleton; an oxime ester-based photopolymerization initiator having absorption in at least the h-ray; zirconium nitride; tungsten cesium oxide; a photopolymerizable monomer; a thermosetting resin; and an inorganic filler other than the zirconium nitride and tungsten cesium oxide, comprising 30% to 50% by mass on a solid content basis relative to the total mass of the composition, wherein the minimum absorbance in a resin layer with a thickness of 30 μm is 1 or more at wavelengths of 480 nm to 780 nm and 780 nm to 1500 nm, and the absorbance at a wavelength of 365 nm is 1.3 or more.

2. The photosensitive resin composition according to claim 1, wherein the carboxyl group-containing resin has a cresol novolac type skeleton.

3. The photosensitive resin composition according to claim 1, further comprising a photopolymerization initiator that does not absorb h rays.

4. The photosensitive resin composition according to claim 1, wherein the photopolymerizable monomer comprises a photopolymerizable monomer with four or more functionalities.

5. The photosensitive resin composition according to claim 1, wherein the thermosetting resin comprises at least one selected from the group consisting of epoxy resins having a phenol novolac type skeleton and epoxy resins having an alicyclic skeleton.

6. The photosensitive resin composition according to claim 1, wherein the inorganic filler has an average particle size (D50) of 10 nm to 2000 nm.

7. A dry film comprising a first film and a resin layer disposed on one side of the first film, wherein the resin layer is formed from the photosensitive resin composition described in claim 1.

8. A photosensitive resin composition according to any one of claims 1 to 6, or a cured product of the resin layer of a dry film according to claim 7.

9. The cured product according to claim 8, wherein the coefficient of linear expansion at 0°C to 50°C is 20 ppm / °C to 40 ppm / °C, and the glass transition temperature is 150°C or higher.

10. A printed circuit board comprising the cured material described in claim 8.

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