Photosensitive resin composition, method for preparing the same, photosensitive dry film, and application thereof

Abstract

This invention provides a photosensitive resin composition, its preparation method, a photosensitive dry film, and its applications. The photosensitive resin composition, by weight, comprises: 45-65 parts of an alkali-soluble resin, 35-55 parts of a photopolymerizable monomer, 0.08-1.8 parts of a first photoinitiator, and 0.5-5 parts of additives; the first photoinitiator has the structure shown. This invention uses an acridine-modified oxime ester photoinitiator as the core photoinitiator component, achieving a significant improvement in the photosensitivity of the photosensitive resin composition.

Description

Technical Field

[0001] This invention relates to the field of photosensitive resins, and more specifically, to a photosensitive resin composition, its preparation method, a photosensitive dry film, and its applications. Background Technology

[0002] In the fabrication of micro-electronic circuits such as printed circuit boards, lead frames, solar cells, conductor packages, BGA (Ball Grid Array), and CPS (Chip Size Package) packages, photoresist patterns are typically formed using optical etching. For example, in the manufacture of a printed circuit board, a photosensitive layer is first formed on the substrate. A mask with a specific pattern is then used to cover the photosensitive layer, exposing the pattern. The exposed and unexposed areas are then developed using a developer with different solubilities, followed by etching or electroplating to form the pattern. Finally, a stripping agent is used to remove the cured dry film, thus transferring the pattern.

[0003] As electronic devices become thinner and smaller, there are corresponding requirements for PCBs to be more precise, denser, and multilayered. For example, high-precision HDI multilayer boards (high-density interconnect printed circuit boards) have higher requirements for the resolution, photosensitivity, and adhesion to the substrate of the photosensitive resin composition used in optical etching methods.

[0004] In recent years, laser direct imaging (LDI) has become increasingly popular, replacing the traditional film mask + UV parallel exposure method. This direct-image exposure method offers better alignment accuracy and produces highly detailed patterns compared to photomask exposure, making it widely used in the fabrication of high-precision HDI inner layer substrates. In this method, besides using monochromatic light such as lasers as the light source, the substrate is scanned while being illuminated, resulting in a longer exposure time compared to traditional photomask methods. Therefore, to shorten exposure time and improve production efficiency, the sensitivity of the photosensitive resin composition needs to be further increased. I-rays (355nm) or h-rays (405nm) are used as the light source. 405nm lasers are commonly used due to their superior exposure accuracy, enabling the formation of high-density photosensitive resist patterns that were previously difficult to achieve. Therefore, high-precision imported exposure machines, as well as the increasingly popular domestically produced LDI exposure machines, all use 405nm lasers as the exposure source.

[0005] On another front, to achieve higher adhesion and resolution, a common method is to add benzyl methacrylate, styrene, or styrene derivatives as copolymers to the alkali-soluble resin of the photosensitive resin composition, which have better adhesion and rigidity. Alternatively, polyfunctional monomers can be added to the photopolymerizable monomers to increase the crosslinking density. It is speculated that the mechanism is that adding a high content of styrene derivatives to the alkali-soluble resin can increase the glass transition temperature of the resin and increase hydrophobicity, thereby significantly improving adhesion and resolution. However, these two methods have drawbacks: the resulting resin composition has significantly increased resist development and removal times, excessively large removal sheets leading to resist residue, and poor dispersibility during development resulting in more developer agglomerates (dross). All these drawbacks can cause copper circuit damage, vias, short circuits, and other defects, leading to a decrease in the yield of the resist used by downstream PCB manufacturers and a significant reduction in production efficiency.

[0006] Oxime ester photoinitiators are a novel type of pyrolytic free radical photoinitiator that has emerged in recent years. They possess advantages such as high photosensitivity, good compatibility and stability with photoresist compositions, high polymerization rate, conversion rate, and transparency of photosensitive materials, and low photolithography residue, and have been widely used in photoresists. By introducing suitable substituents into oxime ester compounds, various industrial requirements can be met, such as high sensitivity to long-wavelength light between 365 nm and 435 nm, good curing reactivity, high thermal and storage stability, and good solubility. However, the use of known oxime ester compounds as photoinitiators still has significant drawbacks.

[0007] As reported in the powerful patent CN106444282, a photosensitive resin composition containing a carbazole oxime ester initiator, based on its experimental results, requires 50 mJ / cm² light intensity when using an LED light source with higher light intensity. 2 The exposure energies mentioned above show insufficient photosensitivity, and the resolution and adhesion performance also fail to meet the performance requirements of LDI dry film resists for high photosensitivity and high precision. Similarly, the strongly reported novel fluorene oxime ester photoinitiators CN112341359B, special structure oxime esters CN116135889B, CN116444460B, and thiophene-containing oxime ester CN114149517B also show the same results, with significantly insufficient photosensitivity and resolution.

[0008] Furthermore, Asahi Kasei's patent CN106918995B reports the use of a carbazole-containing oxime ester photoinitiator compound in a resin composition, resulting in a photosensitive resin composition with excellent resolution and photosensitivity. However, based on the results of its examples, the exposure method is a traditional method using a higher-intensity LED light source (wavelength 365nm) + a mask. Using a higher-intensity light source requires an energy of 30 mJ / cm².2 The image quality is approximately 70 μm, with a resolution exceeding 70 μm. The patent does not present its photosensitivity under direct laser imaging (LDI 405nm) light source conditions. In fact, because LDI laser light sources have longer wavelengths and much lower illumination intensity than LED light sources, the photosensitivity of general photosensitive resin compositions to LDI laser light sources is far lower than that to traditional LED exposure light sources. Based on the inventors' multiple comparative experiments, the energy of the LED light source is estimated to be 30 mJ / cm². 2 Around 100 mJ / cm², corresponding to an LDI laser source energy expected to exceed 100 mJ / cm². 2 Therefore, its photosensitivity and resolution are significantly lower, and it does not meet the performance requirements of LDI high photosensitivity and high precision dry film resist.

[0009] In summary, the exposure energy of the photosensitive resin compositions in the above-mentioned existing technologies is too high, and there is still much room for improvement in the photosensitivity of the photosensitive resist layer. Moreover, none of them mention information on balancing key performance aspects such as developability and film removal. There is still considerable room for improvement in terms of balancing high photosensitivity, high resolution, high adhesion, and excellent developability and film removal performance to meet the key performance requirements of HDI inner layer boards.

[0010] Therefore, how to provide a photosensitive resin composition that can take into account high photosensitivity, high resolution, high adhesion, and excellent development and removal properties is one of the important technical problems that need to be solved in this field. Summary of the Invention

[0011] The main objective of this invention is to provide a photosensitive resin composition, its preparation method, a photosensitive dry film, and its application, in order to solve the problem that photosensitive resin compositions in the prior art are difficult to simultaneously achieve high photosensitivity, high resolution, high adhesion, and excellent development and film removal performance.

[0012] To achieve the above objectives, a first aspect of the present invention provides a photosensitive resin composition, comprising, by weight: 45 to 65 parts of an alkali-soluble resin, 35 to 55 parts of a photopolymerizable monomer, 0.08 to 1.8 parts of a first photoinitiator, and 0.5 to 5 parts of an additive; the first photoinitiator having the structure shown in Formula I:

[0013]

[0014] Formula I

[0015] In Formula I, R1 is a C1-C12 straight-chain or branched aliphatic alkyl group; R2 and R3 are each independently a C1-C12 straight-chain or branched aliphatic alkyl group, a C3-C15 aliphatic cycloalkyl group, or a C6-C18 aryl group, wherein the hydrogen atom on the aryl group may optionally be substituted by a substituent; the substituent is selected from one or more of the following: C1-C4 straight-chain or branched aliphatic alkyl group, C1-C4 haloalkyl group, C1-C4 alkoxy group, C1-C4 alkanoyl group, C1-C4 ester group, halogen, nitro group, phenyl group, amide group, and cyano group.

[0016] Further, in Formula I, R1 is a C1-C10 straight-chain aliphatic alkyl group; R2 and R3 are each independently a C1-C8 straight-chain or branched aliphatic alkyl group, a C3-C10 aliphatic cycloalkyl group, or a C6-C12 aryl group, wherein the hydrogen atom on the aryl group is optionally substituted by a substituent; the substituent is selected from one or more of methyl, ethyl, trifluoromethyl, halogen, nitro, phenyl, amide, and cyano; preferably, in Formula I, R1 is a C1-C8 straight-chain aliphatic alkyl group; R2 and R3 are each independently a C1-C5 straight-chain or branched aliphatic alkyl group, a C3-C6 aliphatic cycloalkyl group, or a C6-C12 unsubstituted aryl group; more preferably, in Formula I, R1 is methyl, ethyl, or n-octyl; R2 is methyl, ethyl, or phenyl; R3 is methyl, ethyl, or isopropyl; further preferably, the first photoinitiator is selected from one or more of the following compounds: , , , , , , , , .

[0017] Furthermore, based on the total weight of the photosensitive resin composition as 100%, the content of the first photoinitiator is 0.1% to 1.5%.

[0018] Further, by weight, the photosensitive resin composition further includes 0.02 to 0.3 parts of a second photoinitiator, which is a hydrogen donor, and the second photoinitiator is selected from one or more of N-phenylglycine, N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-ethyl-N-phenylglycine, tertiary amines, thiols, mercapto compounds, michidone [4,4'-bis(dimethylamino)benzophenone], 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, quinones, aromatic ketones, acetophenones, acylphosphine oxides, benzoin or benzoin ethers, dialkyl ketals, thioxanones, and dialkylaminobenzoate esters, preferably one or more of N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-phenylglycine, and N-ethyl-N-phenylglycine.

[0019] Further, by weight, the photosensitive resin composition further includes 0.02 to 1.5 parts of a third photoinitiator, which is selected from one or more of acridine derivatives, benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, benzoin methyl ether, benzoin phenyl ether, N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone, 2-ethylanthraquinone, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, benzoin derivatives, triarylamine compounds, oxime esters, coumarin compounds, and oxazole compounds, preferably acridine derivatives; preferably, the third photoinitiator has the structure shown in Formula II:

[0020]

[0021] Formula II

[0022] In Formula II, Rc is hydrogen, a C1-C6 straight-chain or branched aliphatic alkyl group, a substituted or unsubstituted aryl group, or a pyridyl group; more preferably, the third photoinitiator is selected from 9-phenylacridine, 9-methylacridine, 9-ethylacridine, 9-chloroethylacridine, 9-methoxyacridine, 9-ethoxyacridine, 9-(4-methylphenyl)acridine, 9-(4-ethylphenyl)acridine, 1,7-bis(9-methylphenyl)acridine, etc. One or more of the following: 9'-acridyl)heptane, 9-(4-n-propylphenyl)acridine, 9-(4-n-butylphenyl)acridine, 9-(4-tert-butylphenyl)acridine, 9-(4-methoxyphenyl)acridine, 9-(4-ethoxyphenyl)acridine, 9-m-tolylacridine, 9-o-tolylacridine, 9-p-phenylacridine, and 9-p-chlorophenylacridine.

[0023] Furthermore, the alkali-soluble resin is obtained by copolymerization of (meth)acrylic acid copolymer units, (meth)acrylate copolymer units, and styrene copolymer units, and the alkali-soluble resin has the structure shown in Formula III:

[0024]

[0025] Formula III

[0026] In Formula III, R4 and R5 are each independently a hydrogen atom or a methyl group; R6 is selected from substituted or unsubstituted C1-C18 straight-chain or branched alkyl groups, benzyl groups, phenoxyethyl groups, and optionally contains hydroxyl and / or amino groups; R7 is a C1-C3 aliphatic alkyl group, a C1-C3 alkoxy group, an amino group, or a halogen group, and the number of R7 groups on the benzene ring is 0-5; the ratio of x, y, z is (15-35):(20-60):(0-55); preferably, the (meth)acrylate copolymer unit is selected from methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, isooctyl (meth)acrylate, and so on. The styrene copolymer unit is selected from one or more of styrene, α-methylstyrene, benzyl methacrylate, and phenoxyethyl methacrylate.

[0027] Furthermore, the acid value of the alkali-soluble resin is 120 mg KOH / g to 250 mg KOH / g; and / or, the weight-average molecular weight of the alkali-soluble resin is 30,000 to 80,000, and the molecular weight distribution is 1.3 to 2.5; and / or, the polymerization conversion rate of the alkali-soluble resin is ≥97%.

[0028] Furthermore, the photopolymerizable monomer includes a first monomer, a second monomer, and an optional third monomer; the first monomer has the structure shown in Formula IV:

[0029]

[0030] Formula IV

[0031] In formula IV, Rb1 is H or methyl, m and n are integers from 0 to 20, and m+n=1~20; the second monomer has the structure shown in formula V:

[0032]

[0033] Formula V

[0034] In formula V, EO is ethoxy, PO is propoxy, and EO and PO are randomly or block-arranged; Rb2 is H or methyl; p1 and p2 are integers from 0 to 30, q1 and q2 are integers from 0 to 20, p1+p2=2~20, q1+q2=0~20; the third monomer is selected from lauryl methacrylate, octadecyl methacrylate, nonylphenol acrylate, isobornyl acrylate, tetrahydrofuran methyl acrylate, bisphenol A di(meth)acrylate, polyethylene glycol (propylene glycol) di(meth)acrylate, ethoxylated (propoxylated) neopentyl glycol diacrylate, trimethylolpropoxylated... One or more of the following: trimethylolpropane trimethacrylate, ethoxylated (propoxylated)trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate; in the photopolymerizable monomer, the weight ratio of the first monomer to the second monomer is (4~20):(20~80), preferably (4~20):(40~80); based on the total weight of the photopolymerizable monomer and the alkali-soluble resin as 100%, the content of the first monomer is 2%~10%, the content of the second monomer is 10%~35%, and the content of the third monomer is 0%~20%.

[0035] Further, the additive is selected from one or more of dyes, photochromic agents, color-forming heat stabilizers, plasticizers, and antioxidants; preferably, the dye is selected from one or more of peacock green, Victoria blue, diamond green, and basic blue; and / or, the photochromic agent includes leuco dyes and halides, and the leuco dye is selected from tris(4-dimethylaminophenyl)methane and / or bis(4-dimethylaminophenyl)phenylmethane, and the halide is selected from one or more of diphenylmethyl bromide, benzyl bromide, and tribromomethyl sulfone; and / or, the color-forming heat stabilizer is a free radical polymerization inhibitor, more preferably one or more of p-methoxyphenol, hydroquinone, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, and aluminum nitrosophenylhydroxylamine; and / or, the plasticizer is selected from phthalates, o-toluenesulfonamide, p-toluenesulfonamide, tributyl citrate, triethyl citrate, acetyl triethyl citrate, acetyl citrate, etc. Tripropyl citrate, tributyl acetylated citrate, polyethylene glycol, polypropylene glycol, polyethylene glycol alkyl ethers, and polypropylene glycol alkyl ethers; and / or, the antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, triethylene glycol ether-di[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate] The dye comprises one or more of the following: 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, 2,6-di-tert-butyl-4-methylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol); preferably, the dye comprises 0.01 to 0.2 parts by weight; and / or, the photochromic agent comprises 0.01 to 5 parts by weight, more preferably 0.5 to 5 parts by weight; and / or, the color-forming heat stabilizer comprises 0.001 to 1 parts by weight; and / or, the plasticizer comprises 0.5 to 5 parts by weight; and / or, the antioxidant comprises 0.01 to 3 parts by weight.

[0036] A second aspect of the present invention provides a method for preparing the above-mentioned photosensitive resin composition, comprising a process for preparing a first photoinitiator, the process of preparing the first photoinitiator comprising: step S1, diphenylamine and p-methoxybenzoic acid undergo a first reaction to obtain compound 1; step S2, compound 1 undergoes a second reaction to obtain compound 2; the second reaction is a dealkylation reaction; step S3, carbazole and raw material i undergo a third reaction to obtain compound 3; step S4, compound 3 and N-bromosuccinimide undergo a fourth reaction to obtain compound 4; step S5, compound 4 and raw material ii undergo a fifth reaction to obtain compound 5; step S6, compound 5 and compound 2 undergo a sixth reaction to obtain compound 6; step S7, compound 6 and raw material iii undergo a seventh reaction to obtain the first photoinitiator; wherein, the structural formula of compound 1 is as follows: The structural formula of compound 2 is: The structural formula of raw material i is The structural formula of compound 3 is: The structural formula of compound 4 is: The structural formula of raw material ii is The structural formula of compound 5 is: The structural formula of compound 6 is: The structural formula of raw material iii is: R1, R2, and R3 all have the same definition as described above; R1' is hydrogen or a straight-chain or branched aliphatic alkyl group of C1 to C11.

[0037] Further, the first reaction includes a first acylation reaction and an alkaline hydrolysis reaction carried out sequentially; during the first acylation reaction, the molar ratio of diphenylamine to p-methoxybenzoic acid is 1:(1~2); and / or, the first acylation reaction includes: a first stage with a reaction temperature of 160℃~180℃ and a reaction time of 8h~10h and a second stage with a reaction temperature of 230℃~250℃ and a reaction time of 18h~22h; and / or, the first acylation reaction is carried out in the presence of a Lewis acid; preferably, the Lewis acid is zinc chloride; the alkaline hydrolysis reaction has a reaction temperature of 50℃~70℃ and a reaction time of 8h~12h; and / or, the mass concentration of the alkaline solution used in the alkaline hydrolysis reaction is 8wt.%~12wt.%.

[0038] Further, in step S2, the dealkylation reaction includes: a first stage with a reaction temperature of 0℃~5℃ and a reaction time of 0.5h~1.5h and a second stage with a reaction temperature of 20℃~30℃ and a reaction time of 1h~3h; and / or, the second reaction is carried out in the presence of boron tribromide, and the molar ratio of compound 1 to boron tribromide is 1:(1.05~1.2).

[0039] Further, step S3 includes: mixing carbazole with raw material i at a weight ratio of 1:(1.05~1.3) and performing a first stirring at 20℃~30℃; adding glacial acetic acid and performing a second stirring at 20℃~30℃; adding sodium cyanoborohydride at 0℃~5℃ and performing a third stirring at 0℃~5℃ and a fourth stirring at 20℃~30℃ in sequence; preferably, the first stirring time is 10min~20min; and / or, the second stirring time is 3h~5h; and / or, the third stirring time is 20min~40min; and / or, the fourth stirring time is 1h~3h.

[0040] Further, step S4 includes: adding N-bromosuccinimide dropwise to the organic solution of compound 3 at 0℃~5℃ for 15min~25min, and carrying out a fourth reaction at 20℃~30℃ for 1h~3h; preferably, the molar ratio of N-bromosuccinimide to compound 3 is (2~2.5):1; more preferably, the organic solution of compound 3 uses one or more of dichloromethane, trichloromethane, toluene and acetonitrile as solvent.

[0041] Further, step S5 includes: adding raw material ii dropwise to a solution containing compound 4 and zinc powder at 80℃~85℃ for 0.8h~1.2h; then carrying out a fifth reaction at 20℃~30℃ for 1h~3h; preferably, the molar ratio of compound 4 to raw material ii is (0.8~1.2):(0.8~1.2); preferably, the molar ratio of compound 4 to zinc powder is 1:(1~2).

[0042] Further, step S6 includes: mixing compound 5, compound 2, cuprous iodide and cesium carbonate in a molar ratio of 1:(1~1.2):1:(1.5~2.4), and carrying out a sixth reaction at 100℃~120℃ for 14h~18h; preferably, the sixth reaction is carried out in a protective atmosphere, more preferably nitrogen.

[0043] Further, the seventh reaction includes a hydroxylation reaction and a second acylation reaction performed sequentially; the hydroxylation reaction includes: mixing compound 6, hydroxylamine hydrochloride and sodium acetate in a molar ratio of 1:(1~2):(1.5~2.5), and reacting at 80℃~90℃ for 4h~6h to obtain a hydroxylation intermediate; the second acylation reaction includes: adding raw material iii dropwise to the organic solution of the hydroxylation intermediate at 0℃~5℃ for 10min~20min, and reacting at 0℃~5℃ for 1h~3h to obtain a first photoinitiator; the weight ratio of raw material iii to the hydroxylation intermediate is 1:(6~7); preferably, the organic solution of the hydroxylation intermediate uses one or more of dichloromethane, toluene and n-hexane as a solvent.

[0044] A third aspect of the present invention provides a photosensitive dry film prepared from the above-described photosensitive resin composition.

[0045] A fourth aspect of the present invention provides an application of the above-described photosensitive dry film as a pattern transfer material in the fields of printed circuit boards, lead frames, solar cells, and conductor packaging.

[0046] By applying the technical solution of this invention, an acridine-modified oxime ester photoinitiator is used as the core photoinitiator component. Through the synergistic photoinitiation mechanism of the acridine light-absorbing unit and the oxime ester cleavage unit in its molecule, the photosensitivity of the photosensitive resin composition is significantly improved. This achieves a breakthrough in achieving a balanced performance of high resolution, excellent adhesion and rapid development / removal at extremely low initiator addition levels. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0048] Figure 1 The image shows the ultraviolet-visible spectral results of the photosensitive resin composition obtained in Example 1 of this invention.

[0049] Figure 2 This is the ultraviolet-visible spectral detection result of the photosensitive resin composition obtained in Comparative Example 1 of the present invention;

[0050] Figure 3 The results of scanning electron microscopy (SEM) characterization of the head morphology of the photosensitive dry film obtained in Example 1 of this invention are shown. Detailed Implementation

[0051] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the embodiments.

[0052] As described in the background section, existing photosensitive resin compositions suffer from difficulties in simultaneously achieving high photosensitivity, high resolution, high adhesion, and excellent development and removal properties. To address these technical problems, a first aspect of the present invention provides a photosensitive resin composition, comprising, by weight: 45 to 65 parts of an alkali-soluble resin, 35 to 55 parts of a photopolymerizable monomer, 0.08 to 1.8 parts of a first photoinitiator, and 0.5 to 5 parts of an additive; the first photoinitiator has the structure shown in Formula I:

[0053]

[0054] Formula I

[0055] In Formula I, R1 is a C1-C12 straight-chain or branched aliphatic alkyl group; R2 and R3 are each independently a C1-C12 straight-chain or branched aliphatic alkyl group, a C3-C15 aliphatic cycloalkyl group, or a C6-C18 aryl group, wherein the hydrogen atom on the aryl group may optionally be substituted by a substituent; the substituent is selected from one or more of the following: C1-C4 straight-chain or branched aliphatic alkyl group, C1-C4 haloalkyl group, C1-C4 alkoxy group, C1-C4 alkanoyl group, C1-C4 ester group, halogen, nitro group, phenyl group, amide group, and cyano group.

[0056] As mentioned earlier, LDI (Light Diffusion Illumination) exposure methods, which use monochromatic light such as lasers as the light source and illuminate the substrate while scanning it, tend to require longer exposure times compared to previous exposure methods. Therefore, to shorten exposure time and improve production efficiency, it is necessary to increase the sensitivity of the photosensitive resin composition. With the increasing density of printed circuit boards in recent years, the requirements for photosensitive resin compositions used to form resist patterns with higher resolution and better adhesion to the substrate have also increased. In the fabrication of HDI (High-Intensity Distributed) inner layer boards, it is required to form resist patterns with a linewidth / spacing (L / S) of less than 20 / 20 μm, while the requirements for packaging substrates are even higher, requiring the formation of resist patterns with a linewidth / spacing (L / S) of less than 10 / 10 μm. The photosensitivity of dry film resists mainly depends on the initiator system used. Different initiator systems have significantly different sensitivities to the exposure light source, and the initiator system has a great influence on key properties of the photosensitive resin composition, such as resolution, adhesion, resist shape, and exposure depth. Currently, the initiator systems in dry film resists commonly reported in patents for use with LDI 405nm exposure light sources and for PCB pattern transfer mainly fall into the following categories:

[0057] The first category focuses on improving the high sensitivity of photosensitive resin compositions to a 405 nm exposure light source. Currently available high-resolution, high-sensitivity dry film resists used in the fabrication of high-precision HDI inner layer boards generally employ an initiator system combining acridine and its derivatives with a second photoinitiator. Dry film resists using this initiator system exhibit high photosensitivity, allowing exposure energy to be reduced to 15-30 mJ, and also offer superior resolution and adhesion, achieving a resolution of approximately 25 μm. Therefore, this initiator system is commonly used in commercially available dry film resists for HDI inner layer board fabrication. However, this approach cannot meet the requirements of PCB manufacturers to further improve production efficiency and exposure accuracy. Furthermore, the inventors' experimental results show that further increasing the amount of acridine-based initiator does not significantly improve the photosensitivity of the dry film resist, and the rectangularity of the resist head morphology decreases significantly, while the curing degree at the resist bottom is noticeably insufficient. The second type, commonly reported in patents, uses another hexaaryl diimidazole derivative combined with a sensitizer (such as pyrazoline) in dry film resists. However, the inventors' experimental results show that the photosensitivity of this dry film resist under LDI (405 nm) light source conditions is not high, and the resolution achievable by this initiator system is also relatively limited. Furthermore, further increasing the amount of initiator and sensitizer does not significantly improve the photosensitivity of the dry film resist. As mentioned above, the initiator systems commonly reported in existing technologies for dry film resists suitable for LDI 405 nm exposure light sources and used for PCB pattern transfer cannot meet the high photosensitivity, high precision, and high efficiency requirements of PCB clients.

[0058] Therefore, based on this, the present invention employs a bifunctional photoinitiator structure formed by the covalent linkage of an acridine group and an oxime ester group. Through the efficient light absorption and electron acceptor capabilities of the acridine unit for 405 nm laser light, the cleavage mechanism of the oxime ester bond under light irradiation resulting in highly reactive free radicals, and the synergistic effect of the two, the photosensitivity and initiation efficiency of the resulting photosensitive resin composition are significantly improved. Specifically:

[0059] Acridine is a rigid planar fused-ring aromatic system with a conjugated structure exhibiting a significant absorption peak, highly matched to the 405 nm laser wavelength used in LDI lithography machines. Under photoexcitation, the acridine unit can accept photon energy transitions to an excited state and, acting as a strong electron acceptor, abstracts electrons from adjacent hydrogen donors (such as intramolecular tertiary amines or trace hydrogen donor components in the system) via a single electron transfer (SET) mechanism, generating acridine radical anions and hydrogen donor radical cations, providing initial active species for radical chain polymerization. The oxime ester group (-C=NO-) undergoes homolytic cleavage under light irradiation, breaking the CN bond (α-cleavage) to generate acyl radicals and imine radicals. Among them, the acyl radical is a highly active initiator, capable of directly attacking the carbon-carbon double bond of the photopolymerizable monomer, initiating radical polymerization. This cleavage process does not require sensitizers and is a cleavage-type photoinitiation mechanism, characterized by high efficiency, few byproducts, and low residue. The introduction of the oxime ester structure makes the initiator's response efficiency to 405 nm light much higher than that of the traditional benzophenone or diimidazole system, which is the core structural basis for achieving a significant improvement in photosensitivity.

[0060] In addition, in the molecular structure of the acridine-modified oxime ester photoinitiator as shown in Formula I of this invention, the nitrogen atom on the carbazole ring is a tertiary amine. This tertiary amine structure can act as a hydrogen donor, thereby further enhancing photosensitivity through intramolecular synergistic effects. The tertiary amine structure can increase the adhesion between the dry film resist and the copper surface, thereby improving adhesion performance.

[0061] In summary, this invention defines a specific structural formula for acridine-modified oxime ester photoinitiators, which simultaneously possess two highly efficient photoinitiating structural units. This results in extremely high photosensitivity to a 405nm single-wavelength laser source, requiring very low initiator addition. Furthermore, the tertiary amine structural unit in the molecule can increase the water solubility of the initiator, improve its developability, and mitigate development precipitation problems, thereby greatly reducing adverse phenomena such as short circuits or open defects caused by initiator residue.

[0062] Furthermore, in preferred formula I, R1 is a C1-C10 straight-chain aliphatic alkyl group to better control molecular polarity and solubility, and reduce its migration. In order to further adjust electron cloud density and solubility, so that the first photoinitiator has better compatibility in alkali-soluble resin and photopolymerization monomer, and improve photosensitivity uniformity, R2 and R3 are each independently C1-C8 straight-chain or branched aliphatic alkyl group, C3-C10 aliphatic cycloalkyl group, and C6-C12 aryl group. The hydrogen atoms on the aryl group can be optionally replaced by substituents. The substituents are selected from one or more of methyl, ethyl, trifluoromethyl, halogen, nitro, phenyl, amide, and cyano groups.

[0063] Building upon this, to further enhance the synergistic effect of intramolecular electron transfer and free radical generation, thereby more effectively reducing the risk of development precipitation and decreased adhesion caused by initiator residue, it is further preferred that in Formula I, R1 is a C1-C8 straight-chain aliphatic alkyl group; R2 and R3 are each independently a C1-C5 straight-chain or branched aliphatic alkyl group, a C3-C6 aliphatic cycloalkyl group, or a C6-C12 unsubstituted aryl group. More preferably, in Formula I, R1 is methyl, ethyl, or n-octyl; R2 is methyl, ethyl, or phenyl; and R3 is methyl, ethyl, or isopropyl. This further reduces the tendency for crystallization due to excessively long molecules, while maintaining good lipophilicity, allowing for more stable dispersion in alkali-soluble resins and photopolymerizable monomers, ultimately achieving a better synergistic improvement in high photosensitivity, low migration, and excellent developability.

[0064] In several preferred embodiments, the first photoinitiator is selected from one or more of the following compounds: , , , , , , , , The aforementioned specific first photoinitiator structure, through more precise control of the molecular symmetry and electronic effects of substituent combinations, achieves the technical effect of maximizing photoinitiation efficiency and optimizing system stability at low addition levels.

[0065] From the perspective of achieving a more balanced improvement in photosensitivity, resolution, and adhesion, the content of the first photoinitiator is preferably 0.1% to 1.5% based on the total weight of the photosensitive resin composition (100%). When its addition amount is less than 0.1%, the photosensitivity of the resulting dry film resist may be poor; when the addition amount is greater than 1.5%, the surface of the dry film resist cures too quickly, affecting the curing depth and potentially reducing the adhesion of the dry film resist to the copper surface.

[0066] To further improve the sensitivity to light sources with wavelengths of 350-420 nm, in addition to including an acridine-modified oxime ester photoinitiator as shown in Formula I, it is preferable that the above-mentioned photosensitive resin composition may also use a small amount of hydrogen donor, 0.02 to 0.3 parts by weight, as a second photoinitiator, so as to promote the resulting composition to have higher photosensitivity, higher resolution, higher developability and better film removal performance, thereby making it more suitable for manufacturing HDI inner layer plates. Specifically, the second photoinitiator is selected from N-phenylglycine, N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-ethyl-N-phenylglycine, tertiary amines (specifically triethanolamine, 2-dimethylaminoethanol, triethanolamine, ethyl benzoate, ethyl 4-dimethylaminobenzoate, ethyl (2-ethyl)hexyl 4-dimethylaminobenzoate, 4,4'-bis(diethylamino)benzophenone), thiols (specifically butyl-3-mercaptopropionate, trimethylolpropionyltris(2-mercaptoacetate), trimethylolpropionyltris(3-mercaptopropionate)), thiols (specifically 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, 2-amino-5-mercapto-1,3,4-thiadiazole), michidone [4,4'-bis(dimethylamino)benzophenone], 4 4'-Bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, quinones (specifically, 2-ethylanthraquinone, sodium anthraquinone-2-sulfonate, 1,4-dihydroxyanthraquinone, 2-isopropylthioxanthraquinone, 2,4-diethylthioxanthraquinone, 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, camphorquinone), aromatic ketones (specifically, benzophenone, 4-methylbenzophenone, 4-chlorobenzophenone, 4-hydroxybenzophenone, 4,4'-dimethylbenzophenone, 4,4'-bis(diethylamino)benzophenone), acetophenones (specifically, acetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropanone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-4'-methylthio-2-morpholinylpropanone (Irgacure) 907), 2-benzyl-2-dimethylamino-4'-morpholinophenylbutanone (Irgacure 369), acylphosphine oxides (specifically, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (Irgacure TPO), 2,4,6-trimethylbenzoyl-ethoxyphenylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Irgacure 819)).

[0067] The following are some of the following: benzoin or benzoin ethers (specifically, benzoin, benzoin acetate, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, etc.), dialkyl ketals (2,2-dimethoxy-2-phenyl-1-dimethylaminoacetophenone, 2,2-diethoxy-2-phenyl-1-dimethylaminoacetophenone, 2,2-dimethoxy-2-(4-methoxyphenyl)-1-dimethylaminoacetophenone, etc.), thioxanthones (thioxanthone, 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2-chlorothioxanthone, 2-dodecylthioxanthone, 1-chloro-4-propoxythioxanthone, etc.), and dialkylaminobenzoic acid esters (methyl p-dimethylaminobenzoate, octyl p-dimethylaminobenzoate, ethyl p-diethylaminobenzoate, 2-ethylhexyl-4-(dimethylamino)benzoate). Among them, due to its better sensitizing effect, one or more of N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-phenylglycine and N-ethyl-N-phenylglycine are preferred.

[0068] In order to complement the absorption spectrum of the first photoinitiator and further improve the uniformity of exposure depth and enhance the thick film curing ability, the photosensitive resin composition is further preferably composed of 0.02 to 1.5 parts by weight of a third photoinitiator. Specifically, the third photoinitiator can be selected from acridine derivatives, benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, benzoin methyl ether, benzoin phenyl ether, N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone, 2-ethylanthraquinone, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, benzoin derivatives (such as benzoin dimethyl ketal), and triarylamine compounds (specifically, N,N'-bis[4-(2-phenylvinyl-1-yl)-phenyl]-N,N'-bis(2-ethyl-6-yl)-phenyl) (-methylphenyl)-1,1'-biphenyl-4,4'-diamine, N,N'-bis[4-(2-phenylvinyl-1-yl)-phenyl]-N,N'-bis(4-butylphenyl)-1,1'-biphenyl-4,4'-diamine, etc.), oxime esters (specifically, 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyl oxime)OXE01, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]acetone 1-(O-acetyl oxime)OXE02, etc.), coumarin compounds (specifically, 7-methylamino-4-methylcoumarin, 7-dimethylamino-4-methylcoumarin, 7- One or more of amino-4-methylcoumarin, 4,6-diethyl-7-ethylaminocoumarin, 7-diethylamino-4-methylcoumarin, 7-ethylamino-4-methylcoumarin, 4,6-dimethyl-7-ethylaminocoumarin, 4,6-dimethyl-7-diethylaminocoumarin, 4,6-diethyl-7-diethylaminocoumarin, 4,6-dimethyl-7-dimethylaminocoumarin, 4,6-dimethyl-7-dimethylaminocoumarin, 4,6-dimethyl-7-ethylaminocoumarin) and oxazole compounds (specifically, 2-(2'-hydroxyphenyl)benzoxazole, 2-phenyl-4-benzylmethyl-5-oxazolone, etc.) are available. Among them, the preferred third photoinitiator is an acridine derivative, which belongs to the same acridine system as the first photoinitiator. Its absorption peaks overlap, and its excited state energy can be transferred, forming a more significant synergistic effect and further improving photosensitivity.

[0069] Furthermore, the third photoinitiator acridine derivative has the structure shown in Formula II:

[0070]

[0071] Formula II

[0072] In Formula II, Rc is hydrogen, a C1-C6 straight-chain or branched aliphatic alkyl group, a substituted or unsubstituted aryl group, or a pyridyl group. Formula II has a well-defined structure, stable light absorption characteristics, and does not compete with the first photoinitiator, thus more stably improving photoinitiation efficiency. The substituted aryl group can be a haloaryl group. The acridine derivatives in Formula II above are commercially available products, and examples include one or more of the following: 9-phenylacridine, 9-methylacridine, 9-ethylacridine, 9-chloroethylacridine, 9-methoxyacridine, 9-ethoxyacridine, 9-(4-methylphenyl)acridine, 9-(4-ethylphenyl)acridine, 1,7-bis(9,9'-acridyl)heptane, 9-(4-n-propylphenyl)acridine, 9-(4-n-butylphenyl)acridine, 9-(4-tert-butylphenyl)acridine, 9-(4-methoxyphenyl)acridine, 9-(4-ethoxyphenyl)acridine, 9-m-tolylacridine, 9-o-tolylacridine, 9-p-phenylacridine, and 9-p-chlorophenylacridine.

[0073] Furthermore, the alkali-soluble resin is obtained by copolymerization of (meth)acrylic acid copolymer units, (meth)acrylate copolymer units, and styrene copolymer units, and the alkali-soluble resin has the structure shown in Formula III:

[0074]

[0075] Formula III

[0076] In Formula III, R4 and R5 are each independently a hydrogen atom or a methyl group; R6 is selected from substituted or unsubstituted C1-C18 straight-chain or branched alkyl groups, benzyl groups, and phenoxyethyl groups, and the straight-chain or branched alkyl groups may optionally contain hydroxyl and / or amino groups; R7 is a C1-C3 aliphatic alkyl group, a C1-C3 alkoxy group, an amino group, or a halogen group, and the number of R7 groups on the benzene ring is 0-5; the ratio of x, y, z is (15-35):(20-60):(0-55). The preferred molecular structure of the above-mentioned alkali-soluble resin can achieve superior developability, higher resolution, and stronger adhesion by controlling the synergistic balance of carboxyl group density, hydrophobicity, and glass transition temperature. In practical applications, the (meth)acrylate copolymer units are selected from one or more of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, lauryl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N,N-dimethyl(meth)acrylate, N,N-diethyl(meth)acrylate, propyl methacrylate, butyl methacrylate, N,N-diethyl(meth)acrylate, benzyl methacrylate, and phenoxyethyl methacrylate; and / or, the styrene copolymer units are selected from one or more of styrene, α-methylstyrene, benzyl methacrylate, and phenoxyethyl methacrylate. When the (meth)acrylate copolymer unit is benzyl (meth)acrylate, a styrene copolymer unit is not required. In practical applications, the above-mentioned alkali-soluble copolymer resin can be a copolymer resin as shown in general structural formula III, or it can be compounded from two or more copolymer resins of this type with different molecular weights, different acid values, or different styrene contents.

[0077] In several preferred embodiments, the acid value of the alkali-soluble resin is 120 mg KOH / g to 250 mg KOH / g, thereby synergistically improving alkali solubility, developability, and resolution, while shortening the film removal time. Preferably, the weight-average molecular weight of the alkali-soluble resin is 30,000 to 80,000 to facilitate the formation of a denser cross-linked network, further enhancing the mechanical strength of the cured dry film, and also more effectively avoiding excessive viscosity and uneven coating caused by excessively high molecular weight. A preferred molecular weight distribution of 1.3 to 2.5 allows for more controllable polymerization, further reducing the risk of precipitation during development. A polymerization conversion rate of ≥97% for the alkali-soluble resin means minimal unreacted monomers, reducing the migration of residual monomers, optimizing the curing depth, and resulting in a more stable performance of the finally cured dry film during storage and exposure, better meeting the high-yield production requirements of HDI.

[0078] To further improve the adhesion and film removal properties of the obtained photosensitive resin composition, it is further preferred that the photopolymerizable monomers include a first monomer, a second monomer, and an optional third monomer; the first monomer has the structure shown in Formula IV:

[0079]

[0080] Formula IV

[0081] In formula IV, Rb1 is H or methyl, m and n are integers from 0 to 20, and m+n=1~20; the second monomer has the structure shown in formula V:

[0082]

[0083] Formula V

[0084] In Formula V, EO is ethoxy, PO is propoxy, and EO and PO are randomly or block-arranged; Rb2 is H or methyl; p1 and p2 are integers from 0 to 30, q1 and q2 are integers from 0 to 20, p1+p2=2~20, q1+q2=0~20; the third monomer is selected from one or more of the following: lauryl methacrylate, octadecyl methacrylate, nonylphenol acrylate, isobornyl acrylate, tetrahydrofuran methyl acrylate, bisphenol A dimethacrylate, polyethylene glycol (propylene glycol) dimethacrylate, ethoxylated (propoxylated) neopentyl glycol diacrylate, trimethylolpropane trimethacrylate, ethoxylated (propoxylated) trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate.

[0085] The first monomer, with the structural formula of Formula IV, contains a benzene ring in its molecule, possessing suitable rigidity. This further enhances the hardness and mechanical strength of the cured dry film, as well as its resistance to chemical reagents. This ensures that even after undergoing a series of pressure spraying and prolonged chemical etching processes, the narrow dry film lines maintain their intact and regular morphology and adhere to the copper-clad laminate substrate. The ethoxy / propoxy modification in its molecular structure also improves flexibility, increases the water solubility, flexibility, and system compatibility of the photosensitive resin composition, thereby improving developability and preventing problems such as gaps and breaks caused by excessive hardness and brittleness in the cured dry film. More importantly, in conventional photosensitive resin compositions, only alkali-soluble resins possess alkali solubility due to the presence of carboxylic acid groups. However, the preferred embodiment of this invention, by introducing a certain proportion of acidic carboxylic acid groups into the photopolymerizable monomer, allows the exposed polymer to also possess good alkali solubility, effectively reducing the film removal time, decreasing the size of film fragments, and improving developability. In addition, the carboxylic acid group is a polar group, and the introduction of the carboxylic acid group can enhance the adhesion between the obtained dry film and the copper surface, thereby improving the adhesion performance.

[0086] In summary, the first monomer effectively combines the unique properties of each functional group, further mitigating the contradiction between the adhesion and removal properties of the photosensitive resin composition. At the same time, it endows it with superior adhesion, better removal and development properties, better mechanical strength and flexibility, making it more suitable for manufacturing high-precision PCBs.

[0087] Meanwhile, the second monomer, with the structural formula V, represents a bisphenol A (meth)acrylate modified with ethoxy and propoxy groups. The bisphenol A structure provides higher steric hindrance, thereby further improving linewidth control. The ethoxy chain in its structure also promotes alkali solubility. This second monomer is commercially available for use. The third monomer further enhances the crosslinking network density, improving the etching resistance of the resulting photosensitive resin.

[0088] Furthermore, in order to more effectively control the polar group density and cross-linked network structure, and achieve a better balance between film removal efficiency and mechanical strength, the weight ratio of the first monomer to the second monomer in the above-mentioned photopolymerizable monomers is preferably (4~20):(20~80), more preferably (4~20):(40~80). To provide sufficient carboxylic acid precursor to form a more stable alkali-soluble network after exposure, while also providing sufficient rigidity and cross-linking density to further optimize resolution and side morphology, it is preferable that, based on the total weight of the photopolymerizable monomers and alkali-soluble resin as 100%, the content of the first monomer is 2%~10%, the content of the second monomer is 10%~35%, and the content of the third monomer is 0%~20%.

[0089] In practical applications, additives are selected from one or more of dyes, photochromic agents, color-forming heat stabilizers, plasticizers, and antioxidants. These functional auxiliary components synergistically enhance the processability and stability of the resulting photosensitive resin composition, achieving more uniform coating, more stable storage, higher visual clarity after curing, and no odor pollution. Specifically, the dye is selected from one or more of peacock green, Victoria blue, diamond green, and basic blue; and / or, the photochromic agent includes a leuco dye and a halide, wherein the leuco dye is selected from tris(4-dimethylaminophenyl)methane [leuco crystal violet] and / or bis(4-dimethylaminophenyl)phenylmethane [leuco peacock green], and the halide is selected from one or more of diphenylmethyl bromide, benzyl bromide, and tribromomethyl sulfone; and / or, the color-forming heat stabilizer is a free radical polymerization inhibitor, more preferably p-methoxyphenol, hydroquinone, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, and aluminum nitrosophenylhydroxylamine; and / or, the plasticizer is selected from phthalates (e.g., diethyl phthalate), o-toluenesulfonamide, p-toluenesulfonamide, tributyl citrate, triethyl citrate, acetyl triethyl citrate, and acetyl tri-n-propyl citrate. Tributyl acetyl citrate, polyethylene glycol, polypropylene glycol, polyethylene glycol alkyl ethers, and polypropylene glycol alkyl ethers; and / or, the antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, triethylene glycol ether-di[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1 One or more of the following: 3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, 2,6-di-tert-butyl-4-methylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol). In order to more effectively achieve multi-dimensional process assistance without affecting the photopolymerization reaction, adhesion, development precipitation, and film removal fragment size, the preferred composition is as follows: the dye is 0.01~0.2 parts by weight; and / or the photochromic agent is 0.01~5 parts by weight, more preferably 0.5~5 parts by weight; and / or the color-forming heat stabilizer is 0.001~1 parts by weight; and / or the plasticizer is 0.5~5 parts by weight; and / or the antioxidant is 0.01~3 parts by weight.

[0090] A second aspect of the present invention provides a method for preparing the above-mentioned photosensitive resin composition, comprising a process for preparing a first photoinitiator, the process of preparing the first photoinitiator comprising: step S1, diphenylamine and p-methoxybenzoic acid undergo a first reaction to obtain compound 1; step S2, compound 1 undergoes a second reaction to obtain compound 2; the second reaction is a dealkylation reaction; step S3, carbazole and raw material i undergo a third reaction to obtain compound 3; step S4, compound 3 and N-bromosuccinimide undergo a fourth reaction to obtain compound 4; step S5, compound 4 and raw material ii undergo a fifth reaction to obtain compound 5; step S6, compound 5 and compound 2 undergo a sixth reaction to obtain compound 6; step S7, compound 6 and raw material iii undergo a seventh reaction to obtain the first photoinitiator; wherein, the structural formula of compound 1 is as follows: The structural formula of compound 2 is: The structural formula of raw material i is The structural formula of compound 3 is: The structural formula of compound 4 is: The structural formula of raw material ii is The structural formula of compound 5 is: The structural formula of compound 6 is: The structural formula of raw material iii is: R1, R2, and R3 all have the same definition as described above; R1' is hydrogen or a straight-chain or branched aliphatic alkyl group of C1 to C11.

[0091] Further, the first reaction includes a first acylation reaction and an alkaline hydrolysis reaction carried out sequentially; during the first acylation reaction, the molar ratio of diphenylamine to p-methoxybenzoic acid is 1:(1~2); and / or, the first acylation reaction includes: a first stage with a reaction temperature of 160℃~180℃ and a reaction time of 8h~10h, and a second stage with a reaction temperature of 230℃~250℃ and a reaction time of 18h~22h; and / or, the first acylation reaction is carried out in the presence of a Lewis acid. In the Friedel-Crafts reaction, i.e., the first acylation reaction, by optimizing the above reaction condition parameters, complete acylation can be promoted, excessive condensation can be avoided, and the technical effect of highly selectively generating the target intermediate compound 1 without byproduct residue can be achieved. Preferring zinc chloride as the Lewis acid can further improve the reaction rate and yield. Subsequently, during the alkaline hydrolysis reaction, the preferred reaction temperature is 50℃~70℃, and the reaction time is 8h~12h; and / or, the mass concentration of the alkaline solution used in the alkaline hydrolysis reaction is 8wt.%~12wt.%. These mild alkaline hydrolysis reaction conditions better protect the ester bonds, preventing their breakage, and also more effectively retain the carboxylic acid groups, providing a more stable and pure precursor for the subsequent demethylation reaction.

[0092] In step S2, the preferred dealkylation reaction includes: a first stage with a reaction temperature of 0°C to 5°C and a reaction time of 0.5 h to 1.5 h, and a second stage with a reaction temperature of 20°C to 30°C and a reaction time of 1 h to 3 h; and / or, the second reaction is carried out in the presence of boron tribromide, and the molar ratio of compound 1 to boron tribromide is 1:(1.05~1.2). In the above reaction process, the first low-temperature stage can reduce side reactions caused by intense exothermic reactions, while the second high-temperature stage promotes more complete dealkylation. The preferred amount of boron tribromide can reduce over-bromination, providing a purer intermediate for subsequent carbazole coupling, and improving the structural purity and photochemical activity of the final first photoinitiator. In general, the preferred conditions and parameters of the above dealkylation reaction can achieve the technical effect of efficiently removing methoxy groups without destroying the amide bond and aromatic ring structure.

[0093] In several typical embodiments, to synthesize compound 3 with higher selectivity while minimizing excessive alkylation byproducts, step S3 preferably includes: mixing carbazole with starting material i at a weight ratio of 1:(1.05~1.3) and performing a first stirring at 20°C~30°C; adding glacial acetic acid and performing a second stirring at 20°C~30°C; adding sodium cyanoborohydride at 0°C~5°C, and sequentially performing a third stirring at 0°C~5°C and a fourth stirring at 20°C~30°C. Regarding the reaction time for each stage, preferably: the first stirring time is 10 min~20 min; and / or, the second stirring time is 3 h~5 h; and / or, the third stirring time is 20 min~40 min; and / or, the fourth stirring time is 1 h~3 h. The first stirring at 20~30°C for 10~20 min promotes more complete contact between carbazole and the aldehyde (starting material i) to form an imine intermediate. The second stirring stabilizes the imine and reduces unreacted starting material residue. The third stirring at 0–5°C for 20–40 min promotes the slow reduction of sodium cyanoborohydride, reducing over-reduction or side reactions. The fourth stirring for 1–3 h ensures a more complete reduction reaction, further improving the conversion rate.

[0094] Regarding the amounts of each raw material used in the above reaction process, in order to achieve more efficient and selective reduction to generate compound 3, reduce the generation of dialkylation or hydrazine impurities, and thus provide intermediates with higher purity for subsequent bromination and coupling, it is preferred that: based on the total weight of carbazole and raw material i as 100%, the molar ratio of carbazole to glacial acetic acid is 1:(0.005~0.05); and / or, the molar ratio of carbazole to sodium cyanoborohydride is 1:(4.0~6.0).

[0095] In step S4, it preferably includes: adding N-bromosuccinimide dropwise to the organic solution of compound 3 at 0°C to 5°C for 15 to 25 minutes, and then carrying out a fourth reaction at 20°C to 30°C for 1 to 3 hours. In this preferred embodiment, the low-temperature dropwise addition reduces the risk of dibromination or ring-top side reactions caused by excessively high local concentrations, while also promoting the slow release of bromine radicals. Optimization of subsequent reaction conditions allows for more complete conversion, providing a higher purity starting material for subsequent reductive coupling. Furthermore, the molar ratio of N-bromosuccinimide to compound 3 is preferably (2 to 2.5):1, to obtain more complete bromination without initiating excessive bromination, providing a more reliable intermediate for subsequent synthesis. In practical applications, the organic solution of compound 3 can be one or more of dichloromethane, chloroform, toluene, and acetonitrile as a solvent.

[0096] Furthermore, to achieve the technical effect of highly selectively generating cycloalkyl-substituted carbazole structures with fewer byproducts and stable yields, step S5 preferably includes: adding raw material ii dropwise to a solution containing compound 4 and zinc powder at 80°C to 85°C for 0.8 h to 1.2 h; followed by a fifth reaction at 20°C to 30°C for 1 h to 3 h. To construct the target structure with higher selectivity and promote more complete reaction between the components, the preferred molar ratio of compound 4 to raw material ii is (0.8 to 1.2):(0.8 to 1.2). Simultaneously, the preferred molar ratio of compound 4 to zinc powder is 1:(1 to 2) to more effectively activate the C-Br bond, improving reaction efficiency and product purity.

[0097] In step S6, it preferably includes: mixing compound 5, compound 2, cuprous iodide, and cesium carbonate in a molar ratio of 1:(1~1.2):1:(1.5~2.4), and carrying out a sixth reaction at 100℃~120℃ for 14h~18h. Cuprous iodide is used to catalyze aryl-heteroaryl coupling, while cesium carbonate acts as a strong base to promote deprotonation. Performing the above steps according to the preferred feed ratio and reaction parameters can more efficiently construct C-C coupling bonds, while also suppressing side reactions, reducing dimer or isomer impurities, and more effectively improving product purity. To further improve product purity, the sixth reaction is preferably carried out under a protective atmosphere, more preferably nitrogen.

[0098] In several typical embodiments, the seventh reaction preferably includes a sequential hydroxylamine reaction followed by a second acylation reaction. The hydroxylamine reaction involves mixing compound 6, hydroxylamine hydrochloride, and sodium acetate in a molar ratio of 1:(1~2):(1.5~2.5), and reacting at 80°C~90°C for 4~6 hours to obtain the hydroxylamine intermediate. This feed ratio promotes complete reaction of the hydroxylamine, and the sodium acetate neutralizes the hydrochloric acid, better maintaining the pH stability of the system. The optimized reaction temperature and time achieve the technical effect of highly selectively generating the hydroxylamine intermediate while avoiding the formation of byproducts such as hydrazine or nitrosamines.

[0099] Based on the above hydroxylation reaction, the preferred second acylation reaction includes: adding raw material iii dropwise to an organic solution of the hydroxylation intermediate at 0°C to 5°C for 10 to 20 minutes, and then reacting at 0°C to 5°C for 1 to 3 hours to obtain the first photoinitiator; the weight ratio of raw material iii to the hydroxylation intermediate is 1:(6 to 7). Based on this preferred scheme, by controlling the reaction selectivity through low temperature and slow acylation, high-purity oxime esterification without excessive acetylation or decomposition is achieved, resulting in a first photoinitiator with superior performance and higher purity, ultimately significantly improving the various properties of the photosensitive resin composition in which it is contained.

[0100] In practical applications, organic solutions of hydroxylamine intermediates can use one or more of dichloromethane, toluene, and n-hexane as solvents.

[0101] A third aspect of the present invention provides a photosensitive dry film prepared from the above-described photosensitive resin composition.

[0102] A fourth aspect of the present invention provides an application of the above-described photosensitive dry film as a pattern transfer material in the fields of printed circuit boards, lead frames, solar cells, and conductor packaging.

[0103] The present application will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed in the present application.

[0104] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0105] Synthesis section:

[0106] I. Synthesis of the First Photoinitiator

[0107] First photoinitiator C-1

[0108] (1) Diphenylamine (33.8 g, 0.2 mol), p-methoxybenzoic acid (45.6 g, 0.3 mol), and zinc chloride (81.6 g, 0.6 mol) were added to a 1.2 L electrically heated enamel-lined reactor. After the addition was completed, the reactor was heated to 170 °C and reacted in a molten state for 8-10 h. Then the temperature was raised to 230-250 °C and reacted for about 20 h. The reactor was cooled to 80 °C and water (500 mL) was added. The mixture was stirred for minutes, and the temperature was kept above 60 °C during the water washing process. The resulting suspension was filtered under reduced pressure, and the solid was collected and placed in a 2 L beaker. Toluene (500 mL) was added to dissolve the solid, resulting in a darker-colored solution. The solution was transferred to a 2 L stainless steel reactor, and 10 wt% sodium hydroxide solution (1 L) was added. The reactor was heated to 60 °C and stirred for 10 h to carry out the alkaline hydrolysis reaction. After the alkaline hydrolysis reaction is complete, remove the alkaline phase, add toluene (500 mL) to the organic phase, and wash three times with water (500 mL each time). 3) The organic phase after washing with water was dried with anhydrous sodium sulfate, filtered, and the filtrate was distilled under reduced pressure using a rotary evaporator to obtain the crude product. The obtained crude solid product was dispersed in a mixed solution of petroleum ether and ethyl acetate (6:1) (600 mL), stirred at room temperature for 30 min, filtered, and the solid was collected. After removing the small amount of solvent encapsulated in the solid by reduced pressure distillation using a rotary evaporator, the initiator intermediate product compound 1 (41.8 g, purity 93%) was obtained as shown in the figure below. 1 H-NMR (CDCl3, 400MHz): 8.318-8.296 (d, 2H), 7.816- 7.776 (t, 2H), 7.744-7.722 (d, 2H), 7.658-7.600 (m, 3H), 7.480-7.426 (m, 3 H), 3.776 (s, 3H). Ms(m / z):286 (M+1) + .

[0109] (2) In a 500 mL three-necked flask, add intermediate compound 1 (40 g, 0.135 mol) and dichloromethane (300 mL) and place in an ice-water bath. At 0-5 °C, slowly add boron tribromide (37.1 g) dropwise over 1 h. After the addition is complete, raise the temperature to room temperature and react for 2 h. Stop the reaction after TLC detection shows complete consumption of the starting material. After the reaction is complete, pour the reaction mixture into ice water (500 g). Extract the resulting mixture with dichloromethane solution twice, using 500 mL each time. Combine the resulting organic phases and extract twice with saturated brine (300 mL each time). 2) Dry anhydrous sodium sulfate, filter, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. Disperse the obtained crude solid product in a mixed solution of petroleum ether and ethyl acetate (5:1) (500 mL), stir at room temperature for 30 min, filter, collect the solid, and remove the small amount of solvent encapsulated in the solid by reduced pressure distillation using a rotary evaporator to obtain the initiator intermediate product compound 2 (31.2 g, purity 94%) as shown in the figure below. 1 H-NMR (CDCl3, 400MHz): 8.216-8.194 (d, 2H), 7.724- 7.686 (t, 2H), 7.664-7.642 (d, 2H), 7.558-7.482 (m, 3H), 7.386-7.236 (m, 3 H), 5.776 (s, 1H). MS(m / z):272 (M+1) + .

[0110] (3) In a 500 mL three-necked flask, add the intermediate compound carbazole (16.7 g, 0.1 mol), paraformaldehyde (6.0 g), and methanol (200 mL). Stir at room temperature for 15 min, then add 3 drops of glacial acetic acid (approximately 0.1 g). After stirring at room temperature for 4 h, slowly add sodium cyanoborohydride (31.0 g, 0.5 mol) under ice-water bath cooling. After the addition is complete, react in an ice-water bath for 30 min, then stir at room temperature for 2 h. TLC analysis showed complete consumption of the reaction mixture. After the reaction was complete, pour the reaction mixture into water (500 mL). Extract the resulting mixture with ethyl acetate twice, 500 mL each time. Combine the resulting organic phases and extract twice with saturated brine (200 mL each time). 2) Dry the product with anhydrous sodium sulfate, filter it, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. The obtained crude solid product was purified by reverse column chromatography to obtain 9-methylcarbazole (intermediate compound 3) (15.1 g, 95% purity).

[0111] (4) In a 500 mL three-necked flask, add intermediate compound 3 (14.5 g, 80 mmol) and dichloromethane (300 mL) and place in an ice-water bath. At 0-5 °C, slowly add N-bromosuccinimide (NBS, 31.3 g, 0.18 mol) over 20 minutes. After addition, raise the temperature to room temperature and react for 2 h. Monitor the reaction by spot TLC. Stop the reaction when the starting material is completely consumed. After the reaction is complete, pour the reaction mixture into ice water (500 g). Extract the resulting mixture with dichloromethane solution twice (500 mL each time). Combine the resulting organic phases and extract twice with saturated brine (500 mL each time). 2) Dry the product with anhydrous sodium sulfate, filter it, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. Purify the obtained crude solid product by reverse column chromatography to obtain intermediate compound 4 (22.3 g, 95% purity) as shown in the figure below.

[0112] (5) 3,6-Dibromo-9-methylcarbazole (compound 4) (21.0 g, 62 mmol), zinc powder (6.0 g, 93 mmol), and toluene (200 mL) were added to a 500 mL three-necked flask. The mixture was heated to 80 °C and kept at this temperature. Methyl acetate (4.8 g, 65 mmol) was slowly added dropwise at this temperature for 1 h. After the starting material disappeared as detected by TLC, the mixture was cooled to room temperature. Water (200 mL) was added to the reaction solution, and the mixture was stirred and separated. Several phases of anhydrous sodium sulfate were dried, filtered, and the filtrate was distilled under reduced pressure using a rotary evaporator to obtain the crude product. The obtained solid crude product was purified by reverse column chromatography to obtain intermediate compound 5 (16.1 g, 94% purity) as shown in the figure below.

[0113] (6) In a 250 mL three-necked flask, intermediate compound 2 (5.4 g, 20 mmol), intermediate compound 5 (7.2 g, 24 mmol), cuprous iodide (3.8 g, 20 mmol), cesium carbonate (13.0 g, 40 mmol), and N,N-dimethylformamide (100 mL) were added. After purging with nitrogen three times, the mixture was heated to 110 °C and reacted for 16 h. The reaction was stopped after the starting materials were completely consumed by TLC. The reaction solution was cooled to room temperature, and the reaction mixture was poured into water (200 mL). The resulting mixture was extracted with ethyl acetate twice, 150 mL each time. The resulting organic phases were combined and extracted twice with saturated brine (100 mL each time). 2) Dry anhydrous sodium sulfate, filter, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. Disperse the obtained crude solid product in a mixed solution of petroleum ether and ethyl acetate (5:1) (200 mL), stir at room temperature for 30 min, filter, collect the solid, and remove the small amount of solvent encapsulated in the solid by reduced pressure distillation using a rotary evaporator to obtain the intermediate product compound 6 (7.9 g, purity 92%) as shown in the figure below.

[0114] (7-1) In a 100 mL three-necked flask, intermediate compound 6 (7.5 g, 15 mmol), hydroxylamine hydrochloride (1.5 g, 22 mmol), sodium acetate (2.5 g, 30 mmol), ethanol (50 mL), and water (10 mL) were added. The mixture was heated to reflux at 85 °C and stirred for 5 h. After TLC analysis showed complete consumption of the starting materials, the reaction was stopped. The reaction solution was cooled to room temperature, and the reaction mixture was poured into water (100 mL). The resulting mixture was extracted with ethyl acetate twice, 100 mL each time. The resulting organic phases were combined and extracted twice with saturated brine (100 mL each time). 2) Dry the anhydrous sodium sulfate, filter, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. Disperse the obtained crude solid product in a mixed solution of petroleum ether and ethyl acetate (5:1) (100 mL), stir at room temperature for 30 min, filter, collect the solid, dry it using a rotary evaporator, and remove the small amount of solvent trapped in the solid to obtain the hydroxylated intermediate product compound (6.8 g, purity 95%).

[0115] (7-2) The obtained hydroxylated intermediate compound was transferred to a 100 mL three-necked flask, and dichloromethane (50 mL) was added. After dissolving by stirring at room temperature, the reaction was placed in an ice-water bath at 0-5 °C. Acetyl chloride (1.1 g, 14 mmol) was slowly added dropwise over approximately 15 min, and stirring was continued for 2 h. The reaction was stopped when the starting material was completely consumed by TLC. Then, 5 wt% NaHCO3 aqueous solution was added to the above flask to adjust the pH to neutral. The mixture was extracted and separated, and the organic phase was extracted twice with water (50 mL each time). 2) Dry the anhydrous sodium sulfate, filter, and distill the filtrate under reduced pressure using a rotary evaporator to obtain the crude product. Disperse the obtained crude solid product in a mixed solution of petroleum ether and ethyl acetate (3:1) (100 mL), stir at room temperature for 30 min, filter, collect the solid, and remove the small amount of solvent encapsulated in the solid by reduced pressure distillation using a rotary evaporator to obtain acridine-modified oxime ester first photoinitiator C-1 (5.9 g, purity 95%). 1 H-NMR (CDCl3, 400MHz): 8.416-8.396 (d, 2H), 7.924- 7.886 (t, 2H), 7.866-7.844 (d, 2H), 7.758-7.682 (m, 3H), 7.674-7.460 (m, 6 H), 7.588-7.438 (m, 3H), 4.430 (s, 3H), 2.506 (s, 3H), 2.354 (s, 3H). MS(m / z):550 (M+1) + .

[0116] The structural formula of the obtained first photoinitiator C-1 is:

[0117]

[0118] The above synthetic route is shown below:

[0119]

[0120] First photoinitiator C-2

[0121] Except for replacing paraformaldehyde with acetaldehyde in step (3), the synthesis method is basically similar. Initiator C-2 is synthesized by the same method as initiator C-1.

[0122]

[0123] The NMR information for C-2 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.418-8.394 (d, 2H), 7.922- 7.884 (t, 2H), 7.868-7.848 (d, 2H), 7.754-7.684 (m, 3H), 7.676-7.462 (m, 6 H), 7.586-7.436 (m, 3H), 4.432-4.224 (m, 2H), 2.512 (s, 3H), 2.358 (s, 3H), 1.466 (t, 3H).

[0124] First photoinitiator C-3

[0125] Except for replacing paraformaldehyde with acetaldehyde in step (3) and replacing methyl acetate with methyl propionate in step (5), the synthesis methods are basically similar. Initiator C-3 is synthesized by the same method as initiator C-1.

[0126]

[0127] The NMR information for C-3 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.414-8.390 (d, 2H), 7.928- 7.892 (t, 2H), 7.872-7.852 (d, 2H), 7.758-7.688 (m, 3H), 7.670-7.468 (m, 6 H), 7.588-7.434 (m, 3H), 4.436-4.228 (m, 2H), 2.504 (s, 3H), 2.466-2.248 (m, 2H), 1.464 (t, 3H), 1.212 (t, 3H).

[0128] First photoinitiator C-4

[0129] Except for replacing paraformaldehyde with acetaldehyde in step (3), replacing methyl acetate with methyl propionate in step (5), and replacing acetyl chloride with propionyl chloride in step (7), the synthesis methods are basically similar. Initiator C-4 is synthesized by the same method as initiator C-1.

[0130]

[0131] The NMR information for C-4 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.412-8.386 (d, 2H), 7.924- 7.894 (t, 2H), 7.876-7.860 (d, 2H), 7.762-7.682 (m, 3H), 7.672-7.470 (m, 6 H), 7.590-7.436 (m, 3H), 4.442-4.226 (m, 2H), 2.534-2.268 (m, 3H), 2.488-2.286 (m, 2H), 1.460 (t, 3H), 1.312 (t, 3H), 1.210 (t, 3H).

[0132] First photoinitiator C-5

[0133] Except for replacing paraformaldehyde with acetaldehyde in step (3) and replacing acetyl chloride with benzoyl chloride in step (7), the synthesis methods are basically similar. Initiator C-5 is synthesized by the same method as initiator C-1.

[0134]

[0135] The NMR information for C-5 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.422-8.402 (d, 2H), 8.054 (d, 2H), 7.926- 7.888 (t, 2H), 7.872-7.852 (d, 2H), 7.758-7.688 (m, 3H), 7.680-7.466 (m, 6 H), 7.586-7.444 (m, 6 H), 4.446-4.230 (m, 2H), 2.442 (s, 3H), 1.466 (t, 3H).

[0136] First photoinitiator C-6

[0137] Except for replacing paraformaldehyde with acetaldehyde in step (3) and replacing methyl acetate with methyl benzoate in step (5), the synthesis methods are basically similar. Initiator C-6 is synthesized by the same method as initiator C-1.

[0138]

[0139] The NMR information for C-6 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.422-8.402 (d, 2H), 8.224 (d, 2H), 7.926- 7.888 (t, 2H), 7.872-7.852 (d, 2H), 7.758-7.688 (m, 3H), 7.680-7.566 (m, 6 H), 7.564-7.440 (m, 6 H), 4.446-4.230 (m, 2H), 2.504 (s, 3H), 1.466 (t, 3H).

[0140] First photoinitiator C-7

[0141] Except for replacing paraformaldehyde with acetaldehyde in step (3) and replacing acetyl chloride with isobutyryl chloride in step (7), the synthesis methods are basically similar. Initiator C-7 is synthesized by the same method as initiator C-1.

[0142]

[0143] The NMR information for C-7 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.420-8.394 (d, 2H), 7.926- 7.884 (t, 2H), 7.868-7.854 (d, 2H), 7.760-7.684 (m, 3H), 7.672-7.464 (m, 6 H), 7.590-7.442 (m, 3H), 4.432-4.224 (m, 2H), 2.562-2.446 (m, 1H), 2.358 (s, 3H), 1.466 (t, 3H), 1.184 (d, 6H).

[0144] First photoinitiator C-8

[0145] Except for replacing paraformaldehyde with n-octanal in step (3) and replacing acetyl chloride with isobutyryl chloride in step (7), the synthesis methods are basically similar. Initiator C-8 is synthesized by the same method as initiator C-1.

[0146]

[0147] The NMR information for C-8 is as follows: 1H-NMR (CDCl3, 400MHz): 8.412-8.382 (d, 2H), 7.914- 7.878 (t, 2H), 7.862-7.848 (d, 2H), 7.752-7.676 (m, 3H), 7.664-7.454 (m, 6 H), 7.582-7.436 (m, 3H), 4.256 (t, 2H), 2.560-2.442 (m, 1H), 2.354 (s, 3H), 1.886-1.804 (m, 2H), 1.512-1.224 (m, 10H), 1.182 (d, 6H), 0.884 (t, 3H).

[0148] First photoinitiator C-9

[0149] Except for replacing paraformaldehyde with acetaldehyde in step (3) and replacing methyl acetate with methyl cyclopentaneformate in step (5), the synthesis methods are basically similar. Initiator C-9 is synthesized by the same method as initiator C-1.

[0150]

[0151] The NMR information for C-9 is as follows: 1 H-NMR (CDCl3, 400MHz): 8.414-8.392 (d, 2H), 7.920- 7.882 (t, 2H), 7.864-7.842 (d, 2H), 7.752-7.680 (m, 3H), 7.672-7.458 (m, 6 H), 7.580-7.432 (m, 3H), 4.422-4.220 (m, 2H), 3.012-2.912 (m, 1H), 2.522 (s, 3H), 2.112-1.524 (m, 8H), 1.460 (t, 3H).

[0152] Other acridine group-modified oxime ester first photoinitiators, as shown in Formula I, can be synthesized by referring to the synthesis methods of C-1 to C-9 above. The specific operation steps will not be repeated in this specification.

[0153] II. Synthesis of Alkali-Soluble Resin A

[0154] Alkali-soluble resin A-1: ​​Methyl methacrylate: Butyl methacrylate: Styrene = 25:30:15:30, acid value 131 mg KOH / g, weight-average molecular weight measured by GPC is 58000 g / mol, conversion rate 98.0%.

[0155] The preparation is carried out using free radical solution polymerization, including the following steps:

[0156] The monomers corresponding to the respective chain segments in the alkali-soluble resin were all purchased directly. The monomers corresponding to the (meth)acrylic acid copolymer units, (meth)acrylate copolymer units, and styrene copolymer units were mixed evenly according to the weight ratio (i.e., x:y:z) (total 100g) and set aside for later use.

[0157] Then, it was mixed with 1.0 g AIBN photoinitiator, 90 g butanone, and 15 g ethanol, stirred and dissolved. About 35% by mass of the mixed solution was added to a three-necked flask with nitrogen protection and a reflux condenser using a peristaltic pump. The mixture was heated to 80°C in an oil bath and stirred for 1 hour. The remaining mixed solution was then added dropwise over 3 hours. The reaction was continued at this temperature for 4 hours, then the temperature was raised to 90°C. 5 g of butanone solution containing 0.2 g of initiator was added in two separate additions, with an interval of 1 hour between the two additions. After the addition was completed, the mixture was stirred at this temperature for 2 hours to stop the reaction and obtain an alkali-soluble resin.

[0158] For the obtained alkali-soluble copolymer resin, its weight-average molecular weight, molecular weight distribution, and solid content were determined by gel permeation chromatography (GPC). Its acid value was tested by acid-base titration; and its polymerization conversion rate was determined by gas chromatography to detect the content of residual unreacted comonomers.

[0159] III. Synthesis of the first monomer in photopolymerization monomer B

[0160] Synthesis of phthalic acid-based (meth)acrylate B-1 with ethoxy / propoxy modified structure:

[0161] Polyethylene glycol (Mn=200, 40.0 g, 0.2 mol) and dichloromethane (200 mL) were added to a 500 mL three-necked flask. After dissolving by stirring at room temperature, the reaction mixture was placed in an ice-water bath at 0-5°C. Methacrylamide chloride (20.8 g, 0.2 mol) was slowly added dropwise over approximately 30 minutes. The mixture was stirred for another 2 hours under ice-water conditions, and then the reaction was stopped. Then, 5 wt% NaHCO3 aqueous solution was added to the flask to adjust the pH to neutral. The mixture was extracted and separated. The organic phase was extracted twice with water (100 mL each time). 2) Dry the product with anhydrous sodium sulfate, filter, and distill the filtrate under reduced pressure using a rotary evaporator to obtain a monool intermediate (41.0 g). In a three-necked flask, add the obtained monool intermediate (41.0 g), toluene (100 mL), phthalic anhydride (29.6 g, 0.2 mol), p-toluenesulfonic acid catalyst (0.1 g), and 2,6-tert-butyl-p-cresol (0.05 g). Heat to 85-90 °C and react for 6 h, then stop the reaction. Cool the reaction mixture to room temperature, add ethyl acetate (100 mL), and wash the resulting organic mixture twice with 150 mL of water. 2) The organic phase after washing with water was dried with anhydrous sodium sulfate, filtered, and p-hydroxyanisole (0.01 g) was added. Then, the organic solvent was removed by vacuum distillation using a rotary evaporator. The residue was the compound (B-1) of general formula (Ⅲ) (m=5, n=0, Rb1=CH3).

[0162] Following the above synthesis method, B-2 to B-5 were prepared respectively.

[0163] B-2: m=9, n=0, Rb1=CH3);

[0164] B-3: m=5, n=2, Rb1=CH3);

[0165] B-4: m=5, n=2, Rb1=H);

[0166] B-5: m=12, n=6, Rb1=CH3).

[0167] IV. Preparation of Photosensitive Resin Composition

[0168] In addition to the above-mentioned alkali-soluble copolymer resin, photopolymerizable unsaturated monomer, and photopolymerization initiator, the photosensitive resin composition of the present invention also requires additives. The additives are composed of one or more of the following: photochromic agent, color-forming heat stabilizer, plasticizer, and antioxidant, mixed in any proportion.

[0169] According to the formulations in Tables 1-1 to 1-4 below, the components are mixed in proportion, and 60 parts by weight of solvent are added. Suitable solvents for preparing coating solutions include acetone, butanone, methanol, ethanol, isopropanol, toluene, etc. The mixture is then stirred thoroughly until completely dissolved to prepare a resin composition solution with a solid content of 40%. After standing for 30 minutes to fully degas, the solution is evenly coated onto the surface of a 16 μm thick PET support film using a coating machine. The film is then baked in a 90°C oven for 8 minutes to form a 25 μm thick dry film resist layer, which appears blue-green under yellow light. Finally, a 20 μm thick polyethylene film protective layer is laminated onto its surface to obtain a three-layer photosensitive dry film.

[0170] Raw material description:

[0171] Alkali-soluble resin A

[0172] A-1: Methacrylic acid: Methyl methacrylate: Butyl methacrylate: Styrene = 25:30:15:30, acid value 131 mg KOH / g, weight-average molecular weight measured by GPC is 58000 g / mol, conversion rate 98.0%, molecular weight distribution 1.7;

[0173] A-2: Methacrylic acid: Methyl methacrylate: Butyl methacrylate: Styrene = 25:35:15:25, acid value 129 mg KOH / g, weight average molecular weight measured by GPC is 100000 g / mol, conversion rate 97.0%, molecular weight distribution 1.8;

[0174] A-3: Methacrylic acid: Methyl methacrylate: Butyl methacrylate: Styrene = 25:30:15:30, acid value 135 mg KOH / g, weight-average molecular weight measured by GPC is 60000 g / mol, conversion rate 95.0%, molecular weight distribution 3.0;

[0175] Photopolymerizable monomer B

[0176] B-1 to B-5, see the above synthesis section for details;

[0177] B-6: (Ethoxy group number is 10) Ethoxybisphenol A diacrylate (Meiyuan Special Chemicals), which is the second monomer;

[0178] B-7: (6 ethoxy groups) Ethoxylated polypropylene glycol (700) dimethacrylate (Meiyuan Special Chemicals), which is the third monomer;

[0179] B-8: (4 ethoxy groups) Ethoxy nonylphenol acrylate (Meiyuan Special Chemicals), which is the third monomer;

[0180] B-9: (3 ethoxy groups) Ethoxytrimethylolpropane trimethacrylate (Meiyuan Special Chemicals), which is the third monomer.

[0181] Photoinitiator C

[0182] The first photoinitiators C-1 to C-9 are detailed in the synthesis section above;

[0183] Third photoinitiator C-10: 9-Phenylacetidine (Changzhou Qiangli Electronic Materials);

[0184] Second photoinitiator C-11: N-phenylglycine (Changzhou Qiangli Electronic Materials);

[0185] Other conventional photoinitiators:

[0186] C-12: 2,2'-Bis(2-chlorophenyl)-4,4',5,5'-tetraphenylbisimidazole BCIM (Changzhou Qiangli Electronic Materials);

[0187] C-13: 1-Phenyl-3-(biphenyl)-5-(4-tert-butylphenyl)pyrazoline, sensitizer R=tert-butyl as reported in Asahi Kasei patent CN103076718B;

[0188] C-14: Conventional oxime ester photoinitiator OXE-2 (Shanghai Maclean).

[0189] additive

[0190] D-1: Brilliant Green Pigment (Shanghai Bailingwei Chemical Technology Co., Ltd.), dye;

[0191] D-2: Leuco Crystal Violet (Shanghai Maclean), a photochromic agent;

[0192] D-3: p-Toluenesulfonamide (Shanghai TIXIA Chemical), plasticizer;

[0193] D-4: p-tert-butylcatechol (Shanghai Maclean), a free radical polymerization inhibitor and color stabilizer.

[0194] Table 1-1

[0195]

[0196] Table 1-2

[0197]

[0198] Table 1-3

[0199]

[0200] Table 1-4

[0201]

[0202] Test methods and test results, including sample preparation methods (including film application, exposure, development, and film removal) for each embodiment and comparative example, sample evaluation methods, and evaluation results.

[0203] (1) Sample preparation method

[0204] Film application: The copper surface of the copper-clad laminate is polished using a grinding machine, washed with water, micro-etched, and dried with hot air to obtain a bright and fresh copper surface. The film application machine is set with the pressure roller temperature at 110℃, the conveying speed at 1.0m / min, and heat bonding under standard pressure.

[0205] Exposure: After the film was applied, the sample was left to stand for more than 15 minutes. To test the resolution and adhesion performance, the sample was exposed using a Japanese Adtec exposure machine, model IP-6, with a wavelength of 405nm, using a laser direct imaging (LDI) exposure machine. The photosensitivity was tested using a Stouffer 41-step exposure scale, with the number of exposure grids controlled between 16 and 19.

[0206] Development: After exposure, allow the sample to stand for at least 15 minutes. Develop at 30℃ and 1.5 kg / cm² pressure. 2The developer is a 1 wt% sodium carbonate aqueous solution, and the development time is 1.5 to 2.0 times the minimum development time. After development, the sample is washed with water and dried. The minimum development time is defined as the minimum time required for the resist layer in the unexposed areas to completely dissolve.

[0207] Membrane removal: The membrane removal performance was tested using the beaker stirring method. The membrane removal solution was 3.0 wt% NaOH, the temperature was 50℃, and the sample size was 50 mm. The film removal speed is evaluated by testing the film removal time. The shorter the film removal time, the faster the film removal speed. After the film is completely removed, it is magnetically stirred for 30 seconds, and the size of the fragments is observed.

[0208] (2) Evaluation methods

[0209] Sensitivity Evaluation: After the film was applied, the sample was allowed to stand for at least 15 minutes. Exposure was then performed using an Adtec IP-6 405 nm LDI exposure machine. Sensitivity was measured using a Stouffer 41-step exposure scale. After exposure, the sample was sprayed with a 1 wt% sodium carbonate aqueous solution at 30°C, with a development time 2.0 times the minimum development time, to remove unexposed areas. This process resulted in a cured film formed from the cured photosensitive resin composition on the copper surface of the substrate. The exposure amount (mJ / cm²) was measured when the number of remaining segments on the staged exposure scale obtained as the cured film reached 18. 2 The photosensitivity of the photosensitive resin composition was evaluated. A lower value indicates better photosensitivity. The criteria for judgment are as follows.

[0210] ○: 7~12 mJ / cm 2 ;

[0211] △: 13~30 mJ / cm 2 ;

[0212] ×:>30 mJ / cm 2 .

[0213] Resolution evaluation: The prepared photosensitive dry film resin composition was laminated onto a copper-clad laminate using a dry lamination hot-pressing method. The exposure at 18 frames (mJ / cm²) was used to measure the resolution. 2 The process involves exposing a mask with a wiring pattern having a 1:1 ratio of exposed to unexposed portions. After development for twice the minimum development time, the minimum mask width at which the cured resist lines are formed is taken as the resolution value. The mask is then observed using a metallographic microscope or a scanning electron microscope (SEM). The smaller the number read, the better the resolution.

[0214] Adhesion evaluation: Photosensitive dry film resist was laminated onto a copper plate using a dry-press method, with an exposure of 18 frames (mJ / cm²). 2The process involves exposing a mask with a wiring pattern of n:400, containing both exposed and unexposed portions. After development for twice the minimum development time, the mask is observed using a magnifying glass. The minimum mask width that forms the complete cured resist lines is taken as the adhesion value. The smaller the number read, the better the adhesion.

[0215] Side morphology evaluation: After removing the PE film containing the photosensitive dry film resist, a dry film is laminated onto a copper plate using heated rollers. Here, exposure is performed using a mask with a wiring pattern having an exposed and unexposed portion and a width of n:400. After development at 2.0 times the minimum development time, the obtained dry film image is captured using a scanning electron microscope (SEM) to determine the head morphology of the dry film with a linewidth of 20 μm. The judgment criteria are as follows.

[0216] ○: The cross-section of the dry film head is rectangular;

[0217] △: Some sections of the dry film head have an inverted trapezoidal shape;

[0218] ×: The cross-section of the dry film head is severely inverted trapezoidal or the bottom is hollowed out.

[0219] Evaluation of the amount of developing precipitate: After drying, the photosensitive resin layer is peeled off, and 18g of the photosensitive resist is dissolved in 1L of 1% Na2CO3 developing solution. After the photosensitive layer is completely dissolved, the solution is poured into a micro-developer and sprayed and circulated at 30℃ / 0.12MPa pressure for 90 minutes, after which circulation is stopped. The circulating developing solution is then removed and allowed to stand for 7 days. The precipitate is then filtered out using filter paper, dried, and weighed. The weight of the precipitate on the filter paper is compared to the percentage of the initial 18g photosensitive layer. The judgment criteria are as follows.

[0220] ○: 0~0.4%;

[0221] △: 0.4%~0.8%;

[0222] ×: >0.8%.

[0223] Evaluation of film removal time and film fragment size: The test substrates used for the above-mentioned tests of film removal time and film fragment size were subjected to wet-press lamination. After lamination, the samples were allowed to stand for 24 hours. An Adtec IP-6405 nm LDI exposure machine was used, with exposure energy corresponding to 18 divisions of the Stouffer 41-level exposure scale for photosensitivity testing. The above exposure, development, and film removal processes were then performed. The film removal time and film fragment size of the photosensitive dry film resist were evaluated according to the following criteria: The criteria are as follows.

[0224] ○: Film removal time ≤30s, film removal fragment size 5~15mm, fast film removal and no defective phenomenon of film removal fragments getting tangled in the roller;

[0225] △: 30 s < film removal time ≤ 40 s, film removal fragment size 15~30mm, film removal time is too long, film is too large, and production efficiency is too low;

[0226] ×: The film removal time is >40 s, or the size of the film removal fragments is >30 mm. Long film removal time results in low efficiency, and the film removal fragments are too large, which can easily lead to the defect of the film removal fragments getting tangled in the rollers.

[0227] The test results are shown in Table 2.

[0228] Meanwhile, the liquid resin compositions were coated onto a PET support film, baked, and dried to obtain a dry film resist photosensitive layer with a thickness of 25 μm. Subsequently, before exposure, the photosensitive layer samples obtained in Example 1 and Comparative Example 1 were subjected to UV-Vis light tests, and the results are shown below. Figure 1 and Figure 2 .Depend on Figure 1 It can be seen that the photosensitive resin composition obtained in Example 1 has a more obvious absorption peak for a 405nm light source, while the photosensitive resin composition obtained in Comparative Example 1 does not have an obvious absorption peak for a 405nm light source.

[0229] Furthermore, the photosensitive dry film sample obtained in Example 1 was characterized by SEM, and the results are shown in [Figure 1]. Figure 3 .Depend on Figure 3 It can be seen that the linewidth of the photosensitive dry film sample obtained in Example 1 is 20 μm, and its head morphology is rectangular and good.

[0230] Table 2

[0231]

[0232] As can be seen from the above description, Examples 1 to 10 of the present invention all yield photosensitive dry film resist compositions with high photosensitivity, high resolution, excellent development and stripping performance, and can be used to manufacture HDI inner layer boards. Furthermore, due to the excellent photosensitivity of the initiator, the amount of initiator added is extremely low, significantly improving the developability of the dry film resist, mitigating development precipitation problems, and greatly reducing defects such as short circuits or open circuits caused by initiator residue.

[0233] In each comparative example:

[0234] In Comparative Example 1, the initiator system consists of an acridine initiator combined with a second photoinitiator—N-phenylglycine, which is a commonly used initiator system in existing LDI dry film resists on the market. However, its photosensitivity is insufficient and cannot meet the requirements of PCB manufacturers to further improve production efficiency and precision.

[0235] In Comparative Example 2, the amount of acridine initiator added was further increased to improve exposure efficiency, but the experimental results showed that the photosensitivity of the dry film resist was not significantly improved, the rectangularity of the head morphology of the dry film resist was significantly reduced, and the curing degree of the bottom of the resist was significantly insufficient.

[0236] In Comparative Example 3, the initiator system consisted of a hexaaryl diimidazole derivative combined with a pyrazoline photosensitizer reported in an Asahi Kasei patent. This initiator system is another type of initiator system commonly used in LDI dry film resists. However, the experimental results showed that its photosensitivity was insufficient, failing to meet the requirements for high-efficiency production of HDI inner layer boards, and its resolution and adhesion performance did not meet the precision requirements of HDI inner layer boards. A significant drawback of this type of initiator is the low initiation efficiency of the hexaaryl diimidazole derivative, requiring a large amount of initiator to be added. Furthermore, its poor water solubility leads to noticeable development precipitates. These precipitates caused by initiator residue can easily cause short circuits or open circuits during PCB fabrication.

[0237] In Comparative Example 4, the initiator system used was the conventional oxime ester photoinitiator OXE-2. The experimental results showed that its photosensitivity to a 405nm laser light source was extremely low, and its resolution and adhesion performance were also significantly insufficient.

[0238] In Comparative Examples 5 and 6, the ethoxy / propoxy modified phthalic acid structure (meth)acrylate as shown in Formula (III) was not added in the specified amount. The experimental results showed that the film removal time was significantly longer and the film fragments were significantly larger. Longer film removal time leads to lower production efficiency, and larger film fragments are more prone to wrapping around the rollers.

[0239] In various embodiments:

[0240] Comparing Examples 11 and 12 with Example 1, it can be seen that by optimizing the weight content of the first photoinitiator in the photosensitive resin composition, the photosensitivity, resolution, and adhesion can be improved more evenly.

[0241] Comparing Example 13 with Example 2, it can be seen that by including a specific weight part of a second photoinitiator in the preferred photosensitive resin composition, it can form a complementary effect with the first photoinitiator in terms of absorption spectrum, thereby further improving the uniformity of exposure depth and enhancing the thick film curing ability.

[0242] Comparing Example 14 with Example 2, it can be seen that by preferably including a specific amount of hydrogen donor as a third photoinitiator in the photosensitive resin composition, the resulting composition can have higher photosensitivity, higher resolution, higher developability, and better film removal performance, thus making it more suitable for manufacturing HDI inner layer boards.

[0243] Comparing Example 15 with Example 1, it can be seen that by optimizing the weight-average molecular weight of the alkali-soluble resin, film-forming properties, resolution, adhesion, and developability can be balanced.

[0244] Comparing Example 16 with Example 1, it can be seen that by optimizing the molecular weight distribution and polymerization conversion rate of the alkali-soluble resin, more controllable polymerization can be achieved, further reducing the risk of precipitation during development; at the same time, the curing depth is optimized, making the final cured dry film more stable in storage and exposure, which better meets the high-yield production requirements of HDI.

[0245] Comparing Examples 17 and 18 with Example 1, it can be seen that by optimizing the weights of the first monomer, the second monomer, and the optional third monomer in the photopolymerization monomer, the density of polar groups and the crosslinking network structure can be more effectively controlled, achieving a better balance between film removal efficiency and mechanical strength; at the same time, a more stable alkali-soluble network is formed after exposure, while providing sufficient rigidity and crosslinking density, further optimizing resolution and side morphology.

[0246] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those described herein.

[0247] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A photosensitive resin composition, characterized in that, The photosensitive resin composition comprises, by weight, 45 to 65 parts of alkali-soluble resin, 35 to 55 parts of photopolymerizable monomer, 0.08 to 1.8 parts of first photoinitiator, and 0.5 to 5 parts of additives. The first photoinitiator has the structure shown in Formula I: Formula I In Formula I, R1 is a straight-chain or branched aliphatic alkyl group of C1 to C12. R2 and R3 are each independently a straight-chain or branched aliphatic alkyl group of C1 to C12, an aliphatic cycloalkyl group of C3 to C15, or an aryl group of C6 to C18, wherein the hydrogen atoms on the aryl group may optionally be substituted by substituents; The substituent is selected from one or more of the following: C1-C4 straight-chain or branched aliphatic alkyl, C1-C4 haloalkyl, C1-C4 alkoxy, C1-C4 alkylacyl, C1-C4 ester, halogen, nitro, phenyl, amide, and cyano.

2. The photosensitive resin composition according to claim 1, characterized in that, In Formula I, R1 is a C1-C10 straight-chain aliphatic alkyl group; R2 and R3 are each independently a C1-C8 straight-chain or branched aliphatic alkyl group, a C3-C10 aliphatic cycloalkyl group, or a C6-C12 aryl group, wherein the hydrogen atom on the aryl group is optionally substituted by a substituent; the substituent is selected from one or more of methyl, ethyl, trifluoromethyl, halogen, nitro, phenyl, amide, and cyano groups; Preferably, in Formula I, R1 is a C1-C8 straight-chain aliphatic alkyl group; R2 and R3 are each independently a C1-C5 straight-chain or branched aliphatic alkyl group, a C3-C6 aliphatic cycloalkyl group, or a C6-C12 unsubstituted aryl group; More preferably, in Formula I, R1 is methyl, ethyl, or n-octyl; R2 is methyl, ethyl, or phenyl; and R3 is methyl, ethyl, or isopropyl. More preferably, the first photoinitiator is selected from one or more of the following compounds: 、 、 、 、 、 、 、 、 。 3. The photosensitive resin composition according to claim 1 or 2, characterized in that, Based on the total weight of the photosensitive resin composition as 100%, the content of the first photoinitiator is 0.1% to 1.5%.

4. The photosensitive resin composition according to any one of claims 1 to 3, characterized in that, The photosensitive resin composition further comprises 0.02 to 0.3 parts by weight of a second photoinitiator, which is a hydrogen donor, and is selected from one or more of N-phenylglycine, N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-ethyl-N-phenylglycine, tertiary amines, thiols, mercapto compounds, michidone [4,4'-bis(dimethylamino)benzophenone], 4,4'-bis(diethylamino)benzophenone, 4-methoxy-4'-dimethylaminobenzophenone, quinones, aromatic ketones, acetophenones, acylphosphine oxides, benzoin or benzoin ethers, dialkyl ketals, thioxanones, and dialkylaminobenzoates, preferably one or more of N-phenylglycine ethyl ester, N-methyl-N-phenylglycine, N-phenylglycine, and N-ethyl-N-phenylglycine.

5. The photosensitive resin composition according to any one of claims 1 to 4, characterized in that, The photosensitive resin composition further comprises 0.02 to 1.5 parts by weight of a third photoinitiator, wherein the third photoinitiator is selected from one or more of acridine derivatives, benzophenone, N,N'-tetramethyl-4,4'-diaminobenzophenone, benzoin methyl ether, benzoin phenyl ether, N,N'-tetraethyl-4,4'-diaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-benzyl-2-dimethylamino-1-(4-morpholinylphenyl)-butanone, 2-ethylanthraquinone, benzoin methyl ether, benzoin ethyl ether, benzoin phenyl ether, benzoin derivatives, triarylamine compounds, oxime esters, coumarin compounds, and oxazole compounds, preferably the acridine derivatives; Preferably, the third photoinitiator has the structure shown in Formula II: Formula II In Formula II, Rc is hydrogen, a C1-C6 straight-chain or branched aliphatic alkyl group, a substituted or unsubstituted aryl group, or a pyridyl group; More preferably, the third photoinitiator is selected from one or more of 9-phenylacridine, 9-methylacridine, 9-ethylacridine, 9-chloroethylacridine, 9-methoxyacridine, 9-ethoxyacridine, 9-(4-methylphenyl)acridine, 9-(4-ethylphenyl)acridine, 1,7-bis(9,9'-acridyl)heptane, 9-(4-n-propylphenyl)acridine, 9-(4-n-butylphenyl)acridine, 9-(4-tert-butylphenyl)acridine, 9-(4-methoxyphenyl)acridine, 9-(4-ethoxyphenyl)acridine, 9-m-tolylacridine, 9-o-tolylacridine, 9-p-phenylacridine, and 9-p-chlorophenylacridine.

6. The photosensitive resin composition according to any one of claims 1 to 5, characterized in that, The alkali-soluble resin is obtained by copolymerization of (meth)acrylic acid copolymer units, (meth)acrylate copolymer units, and styrene copolymer units, and the alkali-soluble resin has the structure shown in Formula III: Formula III In Formula III, R4 and R5 are each independently a hydrogen atom or a methyl group; R6 is selected from substituted or unsubstituted C1-C18 straight-chain or branched alkyl groups, benzyl groups, phenoxyethyl groups, and the straight-chain or branched alkyl groups may optionally contain hydroxyl and / or amino groups; R7 is a C1-C3 aliphatic alkyl group, a C1-C3 alkoxy group, an amino group, or a halogen group, and the number of R7 groups on the benzene ring is 0-5; the ratio of x, y, z is (15-35):(20-60):(0-55); Preferably, the (meth)acrylate copolymer unit is selected from one or more of methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, isooctyl methacrylate, lauryl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate, glycidyl methacrylate, N,N-dimethyl(meth)acrylate, N,N-diethyl(meth)acrylate, propyl methacrylate, butyl methacrylate, N,N-diethyl(meth)acrylate, benzyl methacrylate, and phenoxyethyl methacrylate; and / or, the styrene copolymer unit is selected from one or more of styrene, α-methylstyrene, benzyl methacrylate, and phenoxyethyl methacrylate.

7. The photosensitive resin composition according to any one of claims 1 to 6, characterized in that, The acid value of the alkali-soluble resin is 120 mg KOH / g to 250 mg KOH / g; and / or, The alkali-soluble resin has a weight-average molecular weight of 30,000 to 80,000 and a molecular weight distribution of 1.3 to 2.5; and / or, The polymerization conversion rate of the alkali-soluble resin is ≥97%.

8. The photosensitive resin composition according to any one of claims 1 to 7, characterized in that, The photopolymerizable monomer includes a first monomer, a second monomer, and an optional third monomer; The first monomer has the structure shown in Formula IV: Formula IV In Formula IV, Rb1 is H or methyl, m and n are integers from 0 to 20, and m+n=1 to 20; The second monomer has the structure shown in equation V: Formula V In formula V, EO is ethoxy, PO is propoxy, and EO and PO are randomly or block-arranged; Rb2 is H or methyl; p1 and p2 are integers from 0 to 30, q1 and q2 are integers from 0 to 20, p1+p2=2~20, q1+q2=0~20; The third monomer is selected from one or more of the following: lauryl methacrylate, octadecyl methacrylate, nonylphenol acrylate, isoborneol acrylate, tetrahydrofuran methyl acrylate, bisphenol A dimethacrylate, polyethylene glycol (propylene glycol) dimethacrylate, ethoxylated (propoxylated) neopentyl glycol diacrylate, trimethylolpropane trimethacrylate, ethoxylated (propoxylated) trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, and dipentaerythritol hexaacrylate. In the photopolymerizable monomer, the weight ratio of the first monomer to the second monomer is (4~20):(20~80), preferably (4~20):(40~80). Based on the total weight of the photopolymerizable monomer and the alkali-soluble resin as 100%, the content of the first monomer is 2% to 10%, the content of the second monomer is 10% to 35%, and the content of the third monomer is 0% to 20%.

9. The photosensitive resin composition according to any one of claims 1 to 8, characterized in that, The additive is selected from one or more of dyes, photochromic agents, color-forming heat stabilizers, plasticizers, and antioxidants; Preferably, the dye is selected from one or more of peacock green, Victoria blue, diamond green, and basic blue; and / or, the photochromic agent includes a leuco dye and a halide, wherein the leuco dye is selected from tris(4-dimethylaminophenyl)methane and / or bis(4-dimethylaminophenyl)phenylmethane, and the halide is selected from one or more of diphenylmethyl bromide, benzyl bromide, and tribromomethyl sulfone; and / or, the color-forming heat stabilizer is a free radical polymerization inhibitor, more preferably one or more of p-methoxyphenol, hydroquinone, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, and aluminum nitrosophenylhydroxylamine; and / or, the plasticizer is selected from phthalates, o-toluenesulfonamide, p-toluenesulfonamide, tributyl citrate, triethyl citrate, acetyl triethyl citrate, acetyl tri-n-propyl citrate, and acetyl tri-n-butyl citrate. Ester, polyethylene glycol, polypropylene glycol, polyethylene glycol alkyl ethers, and polypropylene glycol alkyl ethers; and / or, the antioxidant is selected from pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, triethylene glycol ether-di[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,3,5 One or more of the following: tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexamethylenediamine, 2,6-di-tert-butyl-4-methylphenol, and 2,2'-methylenebis(4-methyl-6-tert-butylphenol); Preferably, the dye is present in parts by weight of 0.01 to 0.2; and / or, the photochromic agent is present in parts by weight of 0.01 to 5, more preferably 0.5 to 5; and / or, the color-forming heat stabilizer is present in parts by weight of 0.001 to 1; and / or, the plasticizer is present in parts by weight of 0.5 to 5; and / or, the antioxidant is present in parts by weight of 0.01 to 3.

10. A method for preparing a photosensitive resin composition according to any one of claims 1 to 9, characterized in that, The process includes preparing the first photoinitiator, which includes: In step S1, diphenylamine reacts with p-methoxybenzoic acid in a first reaction to give compound 1; In step S2, compound 1 undergoes a second reaction to yield compound 2; the second reaction is a dealkylation reaction. In step S3, carbazole reacts with starting material i in a third reaction to yield compound 3; In step S4, compound 3 reacts with N-bromosuccinimide in a fourth reaction to obtain compound 4; In step S5, compound 4 and raw material ii undergo a fifth reaction to obtain compound 5; In step S6, compound 5 and compound 2 undergo a sixth reaction to obtain compound 6; Step S7: Compound 6 and raw material iii undergo a seventh reaction to obtain the first photoinitiator; Wherein, the structural formula of compound 1 is The structural formula of compound 2 is as follows: The structural formula of the raw material i is: The structural formula of compound 3 is as follows: The structural formula of compound 4 is as follows: The structural formula of the raw material ii is: The structural formula of compound 5 is as follows: The structural formula of compound 6 is as follows: The structural formula of the raw material iii is: ; Wherein, R1, R2, and R3 have the same definition as described in any one of claims 1 to 9; R1' is hydrogen, or a straight-chain or branched aliphatic alkyl group of C1 to C11.

11. The method for preparing the photosensitive resin composition according to claim 10, characterized in that, The first reaction includes a first acylation reaction and an alkaline hydrolysis reaction performed sequentially; In the first acylation reaction, the molar ratio of diphenylamine to p-methoxybenzoic acid is 1:(1~2); and / or, the first acylation reaction includes: a first stage with a reaction temperature of 160℃~180℃ and a reaction time of 8h~10h, and a second stage with a reaction temperature of 230℃~250℃ and a reaction time of 18h~22h; and / or, the first acylation reaction is carried out in the presence of a Lewis acid; preferably, the Lewis acid is zinc chloride; The alkaline hydrolysis reaction is carried out at a temperature of 50℃ to 70℃ for 8h to 12h; and / or the mass concentration of the alkaline solution used in the alkaline hydrolysis reaction is 8wt.% to 12wt.%.

12. The method for preparing the photosensitive resin composition according to claim 10 or 11, characterized in that, In step S2 The dealkylation reaction includes: a first stage with a reaction temperature of 0℃~5℃ and a reaction time of 0.5h~1.5h, and a second stage with a reaction temperature of 20℃~30℃ and a reaction time of 1h~3h; and / or, The second reaction is carried out in the presence of boron tribromide, and the molar ratio of compound 1 to boron tribromide is 1:(1.05~1.2).

13. The method for preparing the photosensitive resin composition according to any one of claims 10 to 12, characterized in that, Step S3 includes: mixing the carbazole and the raw material i at a weight ratio of 1:(1.05~1.3) and performing a first stirring at 20℃~30℃; adding glacial acetic acid and performing a second stirring at 20℃~30℃; adding sodium cyanoborohydride at 0℃~5℃ and performing a third stirring at 0℃~5℃ and a fourth stirring at 20℃~30℃ in sequence; Preferably, the first stirring time is 10 min to 20 min; and / or, the second stirring time is 3 h to 5 h; and / or, the third stirring time is 20 min to 40 min; and / or, the fourth stirring time is 1 h to 3 h.

14. The method for preparing the photosensitive resin composition according to any one of claims 10 to 13, characterized in that, Step S4 includes: adding the N-bromosuccinimide dropwise to the organic solution of compound 3 at 0℃~5℃ for 15min~25min, and carrying out the fourth reaction at 20℃~30℃ for 1h~3h. Preferably, the molar ratio of the N-bromosuccinimide to compound 3 is (2~2.5):1; More preferably, the organic solution of compound 3 uses one or more of dichloromethane, trichloromethane, toluene, and acetonitrile as a solvent.

15. The method for preparing the photosensitive resin composition according to any one of claims 10 to 14, characterized in that, Step S5 includes: adding raw material ii dropwise to a solution containing compound 4 and zinc powder at 80℃~85℃ for 0.8h~1.2h; then carrying out the fifth reaction at 20℃~30℃ for 1h~3h. Preferably, the molar ratio of compound 4 to raw material ii is (0.8~1.2):(0.8~1.2). Preferably, the molar ratio of compound 4 to zinc powder is 1:(1~2).

16. The method for preparing the photosensitive resin composition according to any one of claims 10 to 15, characterized in that, Step S6 includes: mixing compound 5, compound 2, cuprous iodide and cesium carbonate in a molar ratio of 1:(1~1.2):1:(1.5~2.4), and carrying out the sixth reaction at 100℃~120℃ for 14h~18h. Preferably, the sixth reaction is carried out in a protective atmosphere, and more preferably, the protective atmosphere is nitrogen.

17. The method for preparing the photosensitive resin composition according to any one of claims 10 to 16, characterized in that, The seventh reaction includes a sequential hydroxylation reaction and a second acylation reaction; The hydroxylation reaction includes: mixing compound 6, hydroxylamine hydrochloride and sodium acetate in a molar ratio of 1:(1~2):(1.5~2.5), and reacting at 80℃~90℃ for 4h~6h to obtain a hydroxylation intermediate; The second acylation reaction includes: adding the raw material iii dropwise to the organic solution of the hydroxylation intermediate at 0℃~5℃ for 10min~20min, and carrying out the reaction at 0℃~5℃ for 1h~3h to obtain the first photoinitiator; the weight ratio of the raw material iii to the hydroxylation intermediate is 1:(6~7). Preferably, the organic solution of the hydroxylamine intermediate uses one or more of dichloromethane, toluene, and n-hexane as a solvent.

18. A photosensitive dry film, characterized in that, The photosensitive dry film is prepared from the photosensitive resin composition according to any one of claims 1 to 9.

19. The application of the photosensitive dry film of claim 18 as a pattern transfer material in the fields of printed circuit boards, lead frames, solar cells, and conductor packaging.

Images