Photosensitive resin composition, solder resist ink, dry film, and cured product

Abstract

The present application relates to a kind of photosensitive resin composition, solder resist ink, dry film and cured product, photosensitive resin composition contains the epoxy acrylic resin of specific structure, the epoxy acrylic resin of specific structure is formed by the addition of α, β unsaturated monobasic acid a1 and monobasic acid a2 with specific structure after the addition of epoxy resin containing two or more than two epoxy groups in one molecule, then add diacid anhydride.The present application can effectively improve the dispersibility of photosensitive resin composition to pigment filler by introducing a certain proportion of monobasic acid a2 with special structure in epoxy acrylate;The water absorption of cured product is reduced, thereby improving the resistance to lead-free tin spraying and wave solder resistance.

Description

Technical Field

[0001] This invention relates to the field of printed circuit board technology, and in particular to a photosensitive resin composition, solder resist ink, dry film, and cured product. Background Technology

[0002] In the field of printed circuit board (PCB) manufacturing, a permanent solder mask layer needs to be formed on the PCB. The solder mask layer serves the following functions: preventing oxidation and corrosion of the circuitry during PCB use and maintaining insulation between circuits. To meet the requirements of high precision, high density, and environmental protection, photosensitive solder mask agents that can be developed with weakly alkaline aqueous solutions have become the mainstream solder mask material for PCBs.

[0003] For circuit boards with through-holes, in order to prevent solder from entering the through-holes or flux from spreading to the back of the circuit board through the through-holes and causing defects, the industry often uses solder resist ink to fill the through-holes, which is completed together with the surface printing of the circuit board.

[0004] Existing US patent US5009982 discloses a photosensitive solder resist composition with a photosensitive resin as the main resin, prepared by adding (meth)acrylic acid to o-cresol-type epoxy resin and then adding a diacid anhydride. This composition exhibits good photosensitivity, resolution, and insulation. However, it still has the following shortcomings:

[0005] A. The ink prepared from the composition is prone to floating color, blooming, or coarsening when stored, indicating insufficient dispersion stability;

[0006] B. When applied to solder mask processes for through-hole filling, if the solder mask layer is left in a normal environment for more than 8 hours after curing, its heat resistance will decrease due to the absorption of moisture from the environment. Simultaneously, during lead-free hot air leveling (lead-free soldering) or lead-free wave soldering, especially since lead-free fluxes are more acidic than leaded fluxes, they strongly attack the ester bonds of the cured material at high temperatures, leading to blistering and peeling of the solder mask layer at through-holes and fine lines. The industry generally avoids this problem by reheating the circuit board, but this adds extra steps and energy consumption, resulting in additional costs.

[0007] C. For carrier circuit boards, the solder mask layer is required to have good HAST (Highly Accelerated Stress Test - Temperature and Humidity) and PCT (Pressure Cooker Test) resistance, which is difficult to guarantee with the technology provided in patent document US5009982.

[0008] Patent document JP1997087346A discloses an energy-curable epoxy acrylate resin composition that can be used in photopolymerizable resins such as solder resists. This composition involves reacting the hydroxyl groups of an epoxy acrylate resin obtained by reacting an epoxy resin with two or more epoxy groups and an unsaturated monobasic acid with a polybasic acid anhydride. Two or more epoxy acrylate resins with different acid values ​​are mixed. The unsaturated monobasic acid used includes acrylic acid or methacrylic acid, their dimer and trimer acids, or hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxybutyl (meth)acrylate. This energy-curable resin can be used in photopolymerizable resins such as solder resists and has advantages such as high sensitivity, excellent solvent drying stability, electrical properties, and electroplating resistance. However, the above-mentioned photosensitive resin composition still suffers from poor hygroscopicity, leading to poor stability. In other words, the heat resistance of the solder mask will decrease after absorbing water from the environment. At the same time, during lead-free hot air leveling (referred to as lead-free spray soldering) or lead-free wave soldering, especially since lead-free flux is more acidic than leaded flux, it has a stronger attack on the ester bonds of the cured material at high temperatures, which makes the solder mask at through holes and fine lines prone to blistering and peeling. Summary of the Invention

[0009] Therefore, it is necessary to provide a photosensitive resin composition, solder resist ink, dry film, and cured product that can improve the dispersibility of pigments and fillers in the photosensitive resin composition, reduce the water absorption of the cured product, and improve the resistance to lead-free tin spraying and wave soldering.

[0010] In a first aspect, this application provides a photosensitive resin composition, characterized in that it contains an epoxy acrylate resin with a specific structure, wherein the epoxy acrylate resin with the specific structure is formed by adding an α,β-unsaturated monobasic acid a1 and a monobasic acid a2 having a specific structure to an epoxy resin containing two or more epoxy groups, followed by adding a diacid anhydride, wherein the monobasic acid a2 having the specific structure conforms to the following structural formula:

[0011]

[0012] Among them, R1 and R2 are hydrogen atoms or hydrocarbon chains with 2-15 carbon atoms, and R1 and R2 cannot be hydrogen atoms at the same time.

[0013] In one embodiment, in the structure of the monocarboxylic acid a2 with a specific structure, R1 and R2 are hydrogen atoms or hydrocarbon chains with 2-12 carbon atoms; preferably, R1 and R2 are hydrogen atoms or hydrocarbon chains with 2-10 carbon atoms. Preferably, the monocarboxylic acid a2 with a specific structure is at least one selected from 2-ethylhexanoic acid, neodecanoic acid, 2-phenylpropionic acid, 2-methylvaleric acid, and 2,2-dimethylvaleric acid.

[0014] In one embodiment, the α,β unsaturated monocarboxylic acid a1 includes at least one of acrylic acid, (meth)acrylic acid, cinnamic acid, and crotonic acid, preferably at least one of methacrylic acid and acrylic acid, and preferably, the α,β unsaturated monocarboxylic acid a1 is (meth)acrylic acid.

[0015] In one embodiment, the molar ratio of the sum of the moles of the α,β unsaturated monocarboxylic acid a1 and the monocarboxylic acid a2 with a specific structure to the molar ratio of the epoxy group is in the range of "0.95-1.1":1; preferably, the molar ratio of a1 to a2 is in the range of 5:5 to 9.5:0.5, more preferably, the molar ratio of a1 to a2 is in the range of 6:4-9:1, and more preferably, the molar ratio of a1 to a2 is in the range of 7:3-9:1.

[0016] In one embodiment, the dicarboxylic anhydride includes one or more of phthalic anhydride, maleic anhydride, methylmaleic anhydride, succinic anhydride, glutaric anhydride, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

[0017] In one embodiment, the epoxy resin used to prepare the epoxy acrylate with the specific structure includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy type epoxy resin, phenolic type epoxy resin, o-cresol type phenolic epoxy resin, biphenol type phenolic epoxy resin, cyclopentadiene type phenolic epoxy resin, and naphthol type phenolic epoxy resin, preferably, o-cresol type phenolic epoxy resin.

[0018] In one embodiment, the amount of the epoxy acrylate resin with the specific structure is 10%-60% of the weight of the photosensitive resin composition, preferably 30%-50%.

[0019] In one embodiment, the photosensitive resin composition further includes an epoxy resin containing two or more epoxy groups as a thermosetting component.

[0020] In one embodiment, the photosensitive resin composition further includes one or more polyacrylate monomers;

[0021] In one embodiment, the photosensitive resin composition further includes one or more photopolymerization initiators.

[0022] In one embodiment, the photosensitive resin composition is used for via filling of circuit boards or for solder resisting of circuit boards.

[0023] In one embodiment, the photosensitive resin composition includes the following components: an epoxy acrylate resin containing a specific structure, an epoxy resin, an acrylate monomer, a photoinitiator, dicyandiamide, a filler, phthalocyanine green, a solvent, and additives, wherein the additives include leveling agents, fumed silica, and defoamers;

[0024] Preferably, the photosensitive resin composition comprises the following components: epoxy acrylate resin with a specific structure, o-cresol-type phenolic epoxy resin, micronized melamine triglycidyl ester, dipentaerythritol hexaacrylate, 2-methyl-1-[4-(methmercapto)phenyl]-2-morpholino-1-propane, 2-isopropyl-thioxanthone, dicyandiamide, micronized barium sulfate, micronized talc, DBE solvent, SOLVESSO 150, leveling agent BYK-354, fumed silica R-972, and defoamer;

[0025] Preferably, the photosensitive resin composition comprises the following components in parts by weight: 42 parts of epoxy acrylate resin containing a specific structure, 5 parts of o-cresol-type phenolic epoxy resin, 4 parts of micronized melamine triglycidyl ester, 5 parts of dipentaerythritol hexaacrylate, 3.5 parts of 2-methyl-1-[4-(methimeryl)phenyl]-2-morpholino-1-propane, 0.8 parts of 2-isopropyl-thioxanthone, 0.3 parts of dicyandiamide, 28 parts of micronized barium sulfate, 4 parts of micronized talc, 4 parts of DBE solvent, 1 part of SOLVESSO 150, 0.2 parts of leveling agent BYK-354, 0.9 parts of fumed silica R-972, and 0.8 parts of defoamer KS-66.

[0026] Secondly, this application provides a solder resist ink comprising the photosensitive resin composition described in any of the above embodiments.

[0027] Thirdly, this application also provides a solder resist dry film having a resin layer formed from the photosensitive resin composition described in any of the above embodiments.

[0028] Fourthly, this application also provides a solder resist cured product, which is obtained by curing the photosensitive resin composition as described in any of the above embodiments, or by curing the solder resist cured product with the solder resist ink as described in any of the above embodiments.

[0029] Compared to existing technologies, the above-mentioned photosensitive resin composition, by introducing a certain proportion of a special-structure monobasic acid α2 into epoxy acrylate, can effectively improve the dispersibility of pigments and fillers in the photosensitive resin composition; reduce the water absorption of the cured product, thereby improving its resistance to lead-free tin spraying and wave soldering. Theoretically, it is speculated that the special-structure monobasic acid has a longer carbon chain and a larger molecular weight, increasing the hydroxyl equivalent of the photosensitive resin composition in the cured product, which can reduce the content of polar hydroxyl groups in the cured product, thus reducing its water absorption; the presence of one or two hydrocarbon groups on the α-carbon of the carboxyl group has a steric hindrance effect on the ester group, further reducing water absorption, and also reducing the attack of flux on the ester bond at high temperatures during lead-free tin spraying and wave soldering processes, making the solder resist layer at through-holes and fine lines less prone to blistering and peeling. Meanwhile, due to the better coating properties of the longer carbon chains on pigments and fillers, they have a better barrier effect. After dispersion, pigments and fillers are less likely to precipitate and agglomerate, which improves the stability of the photosensitive resin composition during storage and makes it less likely to experience floating color or coarsening. Detailed Implementation

[0030] To facilitate understanding of the present invention and to make the above-mentioned objects, features, and advantages of the present invention more apparent, a detailed description of specific embodiments of the present invention is provided below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention, and preferred embodiments are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention. The present invention can be implemented in many other ways different from those described herein, and similar modifications can be made by those skilled in the art without departing from the spirit of the invention; therefore, the present invention is not limited to the specific embodiments disclosed below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0031] In a first aspect, this application provides a photosensitive resin composition, characterized in that it contains an epoxy acrylate resin with a specific structure, wherein the epoxy acrylate resin with the specific structure is formed by adding an α,β-unsaturated monobasic acid a1 and a monobasic acid a2 having a specific structure to an epoxy resin containing two or more epoxy groups, followed by adding a diacid anhydride, wherein the monobasic acid a2 having the specific structure conforms to the following structural formula:

[0032]

[0033] Wherein, R1 and R2 are hydrogen atoms or hydrocarbon chains of 2-15 carbon atoms, and R1 and R2 cannot both be hydrogen atoms. For example, in the structure of a monocarboxylic acid a2 with a specific structure, R1 and R2 are hydrogen atoms or hydrocarbon chains of 2-12 carbon atoms; preferably, R1 and R2 are hydrogen atoms or hydrocarbon chains of 2-10 carbon atoms. Preferably, the monocarboxylic acid a2 with a specific structure is at least one of 2-ethylhexanoic acid, neodecanoic acid, 2-phenylpropionic acid, 2-methylpentanoic acid, and 2,2-dimethylpentanoic acid, but is not limited thereto.

[0034] Compared to existing technologies, the above-mentioned photosensitive resin composition, by introducing a certain proportion of a special-structure monobasic acid α2 into epoxy acrylate, can effectively improve the dispersibility of pigments and fillers in the photosensitive resin composition; reduce the water absorption of the cured product, thereby improving its resistance to lead-free tin spraying and wave soldering. Theoretically, it is speculated that the special-structure monobasic acid has a longer carbon chain and a larger molecular weight, increasing the hydroxyl equivalent of the photosensitive resin composition in the cured product, which can reduce the content of polar hydroxyl groups in the cured product, thus reducing its water absorption; the presence of one or two hydrocarbon groups on the α-carbon of the carboxyl group has a steric hindrance effect on the ester group, further reducing water absorption, and also reducing the attack of flux on the ester bond at high temperatures during lead-free tin spraying and wave soldering processes, making the solder resist layer at through-holes and fine lines less prone to blistering and peeling. Meanwhile, due to the better coating properties of the longer carbon chains on pigments and fillers, they have a better barrier effect. After dispersion, pigments and fillers are less likely to precipitate and agglomerate, which improves the stability of the photosensitive resin composition during storage and makes it less likely to experience floating color or coarsening.

[0035] For example, the preparation process of a specific structure of epoxy acrylate resin is as follows: Epoxy resin is added to a solvent, dissolved, and then reacted with α,β-unsaturated monobasic acid a1 and a monobasic acid a2 having a specific structure. A diacid anhydride is then added to prepare the resin. For example, the solvent is at least one of esters, ketones, ether esters, aromatic hydrocarbons, etc. For example, diethylene glycol monomethyl ether acetate is preferred as the solvent. For example, the preparation process of a specific structure of epoxy acrylate resin is as follows: Air is introduced into the solvent diethylene glycol monomethyl ether acetate, and the mixture is heated to 90°C. O-cresol-type phenolic epoxy resin is added and completely dissolved. Then, α,β-unsaturated monobasic acid a1, monobasic acid a2, hydroquinone monomethyl ether, and triphenylphosphine are added. The mixture is heated to 100°C and reacted for 20 hours until the acid value drops below 3 mg / g. The mixture is then cooled to 90°C, a diacid anhydride is added, and the mixture is reacted for 10 hours to prepare the epoxy acrylate resin with the specific structure.

[0036] The photosensitive resin and its composition provided in this application have excellent dispersion stability for pigments and fillers; the cured product obtained therefrom has excellent moisture resistance, good resistance to lead-free tin spraying and wave soldering, and the solder resist layer at through holes and fine lines is not prone to blistering or peeling.

[0037] In order to solve the problems in the background art of this invention, the applicant conducted in-depth research on photosensitive resin compositions. The results showed that introducing a certain proportion of a monobasic acid a2 with a special structure into epoxy acrylate can effectively improve the dispersibility of pigments and fillers in the photosensitive resin composition; reduce the water absorption of the cured product, thereby improving the resistance to lead-free tin spraying and wave soldering.

[0038] The epoxy acrylate in this invention is obtained by adding an α,β-unsaturated monobasic acid a1 and a monobasic acid a2 with a specific structure to an epoxy resin containing two or more epoxy groups in one molecule, followed by the addition of a diacid anhydride. There are no particular limitations on the epoxy resin used in this application; any molecule containing two or more epoxy groups is acceptable. Examples include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy type epoxy resin, phenolic type epoxy resin, o-cresol type phenolic epoxy resin, biphenol type phenolic epoxy resin, cyclopentadiene type phenolic epoxy resin, naphthol type phenolic epoxy resin, etc. One type of epoxy resin or two or more types can be used. Considering sensitivity, drying properties after pre-baking, and heat resistance, o-cresol type phenolic epoxy resin is preferred.

[0039] In one embodiment, the α,β-unsaturated monocarboxylic acid a1 includes at least one selected from acrylic acid, (meth)acrylic acid, cinnamic acid, and crotonic acid. Preferably, at least one selected from methacrylic acid and acrylic acid is used. More preferably, the α,β-unsaturated monocarboxylic acid a1 is (meth)acrylic acid. It should be noted that the α,β-unsaturated monocarboxylic acid a1 is not particularly limited; any α,β-unsaturated monocarboxylic acid is acceptable, such as (meth)acrylic acid, cinnamic acid, crotonic acid, etc. Preferably, methacrylic acid and acrylic acid are used, and more preferably, acrylic acid is used.

[0040] In one embodiment, the molar ratio of the sum of the moles of the α,β-unsaturated monocarboxylic acid a1 and the monocarboxylic acid a2 with a specific structure to the molar ratio of the epoxy groups ranges from 0.95 to 1.1:1; preferably, the molar ratio of a1 to a2 ranges from 5:5 to 9.5:0.5, more preferably, the molar ratio of a1 to a2 ranges from 6:4 to 9:1, and more preferably, the molar ratio of a1 to a2 ranges from 7:3 to 9:1. It should be noted that the molar ratio of the sum of the moles of the α,β-unsaturated monocarboxylic acid a1 and the monocarboxylic acid a2 with a specific structure to the molar ratio of the epoxy groups in the epoxy resin ranges from 0.9 to 1.1:1, preferably from 0.95 to 1.05:1. If the ratio is too small, it may easily cause gelation or poor developability during the reaction; if the ratio is too large, the acid reaction will be incomplete and is not preferred. The ratio of a1 to a2 is in the range of 5:5 to 9.5:0.5, preferably 6:4 to 9:1, and more preferably 7:3 to 9:1. If the ratio is too low, the photocuring sensitivity will decrease and development will be poor due to the low content of acryloyl groups in the photosensitive resin, which is not preferred. If the ratio is too high, the effect of the present invention cannot be achieved because the proportion of the monobasic acid a2 with a specific structure is too low.

[0041] In one embodiment, the dicarboxylic anhydride includes one or more combinations of phthalic anhydride, maleic anhydride, methylmaleic anhydride, succinic anhydride, glutaric anhydride, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. The dicarboxylic anhydride imparts a certain acid value to the photosensitive resin, giving it weakly basic developability. Examples of dicarboxylic anhydride include phthalic anhydride, maleic anhydride, methylmaleic anhydride, succinic anhydride, glutaric anhydride, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride. One or more combinations of the above-mentioned anhydrides can be used. The acid value of the photosensitive resin is in the range of 30-150 mg / g KOH, preferably 60-120 mg / g KOH, and more preferably 70-100 mg / g KOH. If the acid value is lower than 30 mg / g KOH, the developability is insufficient and it is not preferred. If the acid value exceeds 150 mg / g KOH, it is easy for the developing solution to cause erosion of the exposed part of the solder resist layer and excessive side erosion of the solder barrier during development, and it is not preferred.

[0042] In this application, the reaction of epoxy resin with α,β-unsaturated monocarboxylic acid a1 and a monocarboxylic acid a2 with a specific structure can be carried out using known methods, such as using an inert solvent with a boiling point range of 90-250°C for ease of operation. The reaction typically requires heating, and further, as needed, a thermal inhibitor and a reaction catalyst are added. The reaction temperature is 60-150°C, preferably 70-140°C, more preferably 70-120°C, and the reaction time is 4-32 hours, preferably 8-24 hours. Examples of catalysts include amines such as N,N-dimethylbenzylamine, triethylamine, DMP-30, and imidazoles; quaternary ammonium salts such as triphenylphosphine, triphenylantimony, benzyltrimethylammonium chloride, and benzyltriethylammonium chloride; quaternary phosphine salts such as tetraphenylphosphine bromide and benzyltriphenylphosphine bromide; and organometallic salts such as chromium octoate and zinc octoate. As polymerization inhibitors, phenolic inhibitors such as p-methoxyphenol, hydroquinone, and p-tert-butylphenol can be used.

[0043] For example, the photosensitive resin composition may further include an epoxy resin containing two or more epoxy groups as a thermosetting component, such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy type epoxy resin, phenolic type epoxy resin, o-cresol type phenolic epoxy resin, biphenol type phenolic epoxy resin, cyclopentadiene type phenolic epoxy resin, naphthol type phenolic epoxy resin, etc., triglycidyl cyanurate, copolymerized epoxy-containing acrylic resin with (meth)acrylate and glycidyl methacrylate as monomers, etc., and one or more of these epoxy resins may be used. For example, the epoxy acrylate includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy type epoxy resin, phenolic type epoxy resin, o-cresol type phenolic epoxy resin, biphenyl phenolic epoxy resin, cyclopentadiene type phenolic epoxy resin, and naphthol type phenolic epoxy resin, preferably o-cresol type phenolic epoxy resin.

[0044] In one embodiment, the photosensitive resin composition further includes one or more polyacrylate monomers; the photosensitivity of the composition can be improved by using polyacrylate monomers in the photosensitive resin composition, and examples include dimethacrylates of diols such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate; trimethacrylates of triols such as glycerol tri(meth)acrylate, trihydroxyethyl cyanurate tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, eth(propoxylated trimethylolpropane tri(meth)acrylate, and eth(propoxylated tricyanate tri(meth)acrylate; tetramethacrylates of tetraols such as pentaerythritol tetra(meth)acrylate, di(trimethylolpropane) tetra(meth)acrylate, and eth(propoxylated pentaerythritol tetra(meth)acrylate; dipentaerythritol penta(meth)acrylate; and dipentaerythritol hexa(meth)acrylate. One or more of these polyacrylates may be used.

[0045] In one embodiment, the photosensitive resin composition further includes one or more photopolymerization initiators. Examples of photoinitiators used in the photosensitive resin composition include benzoin and its alkyl ethers, acetophenone, benzoyl dimethyl ketal, and other acetophenones; anthraquinones such as methyl anthraquinone and ethyl anthraquinone; thioxanthones such as 2,4-diethylthioxanthone and 2-isopropylthioxanthone; benzophenones such as tetramethylmirnyl ketone, tetraethylmirnyl ketone, and 4-benzoyl-4'-methyl diphenyl sulfide; α-amino ketones such as 2-methyl-1-[4-(meththio)phenyl]-2-morpholino-1-propane, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)-1-butanone, and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone; and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, bis(2,4,6) Acylphosphine oxides such as 2,4,6-trimethylbenzoyl-ethyl-phenyl-phosphine ester (TPO-L); α-hydroxy ketones such as 1-hydroxy-cyclohexyl-phenyl ketone and 2-hydroxy-2-methyl-1-phenyl-1-propanone; benzoyl esters such as benzoylcarbamate and triethylene benzoate; oxime esters such as 1-[4-(phenylthio)phenyl]-1,2-octanedione, 2-(O-benzoyl oxime) (OXE-01), and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl] ethyl ketone, and 1-(O-acetyl oxime) (OXE-02); and hexaaryl diimidazoles such as bis(2-chlorophenyl)-tetraphenylbiimidazole (BCIM). It can also be used in conjunction with photoinitiators such as tertiary amines like N,N-dimethyl-terephthalate, N,N-diethyl-terephthalate, and triethylamine; and synergists or sensitizers such as coumarins. One or more of these photoinitiators can be used. The proportion of these photoinitiators is 0.01-10% of the total weight of the photosensitive resin composition, preferably 0.1-3%.

[0046] To reduce shrinkage during curing and improve the hardness and electrical insulation of the cured product, the photosensitive resin composition of the present invention may include known inorganic fillers, such as calcium carbonate, crystalline silica, fused silica, silicon carbide, alumina, titanium dioxide, zirconium oxide, talc, and barium sulfate. The proportion of these fillers is 0-60% of the total weight of the photosensitive resin composition, preferably 10-45%.

[0047] To improve the adhesion of the cured material to the copper surface of the circuit board, the photosensitive resin composition may, for example, further include an adhesion additive, which includes at least one of dicyandiamide, melamine, and imidazole compounds. The photosensitive resin composition of the present invention may contain dicyandiamide, melamine, or imidazole compounds. These compounds not only improve adhesion to the copper surface but also help the curing agent promote the curing of the thermosetting epoxy resin component.

[0048] To adapt to screen printing or other coating operations, the photosensitive resin composition of the present invention can be diluted to a suitable working viscosity using one or more solvents such as esters, ketones, ether esters, and aromatics.

[0049] The photosensitive resin composition of the present invention may also use known additives as needed, such as inorganic or organic pigments such as phthalocyanine blue, phthalocyanine green, diazo yellow, carbon black, titanium dioxide, crystal violet, DPP red, and pigment violet; polysiloxane and polyacrylate type defoamers; polysiloxane and polyacrylate type leveling agents; rheology modifiers such as fumed silica and organic modified bentonite; and heat stabilizers such as p-methoxyphenol, 2,6-di-tert-butylphenol, hydroquinone, phenothiazine, and thioethers.

[0050] The photosensitive resin composition of the present invention can be manufactured by mixing the components using known mixing methods such as a three-roll mill, a sand mill, or a ball mill. For ease of storage, the photosensitive resin can be mixed with a photoinitiator, additives, and some fillers to form a first premix; and the epoxy resin, acrylate monomer, and some fillers can be mixed to form a second premix. The first and second premixes are temporarily mixed before use.

[0051] The photosensitive resin composition of the present invention can be coated onto a substrate to the desired thickness using known methods such as screen printing, roller coating, electrostatic spraying, or air spraying. It is then pre-baked at 50-90°C for 30-90 minutes to allow the solvent to evaporate, forming a dry coating. A partially transparent film is placed in contact with the coating, and selective exposure with ultraviolet light is performed to form a latent image. Development is performed using a 0.6-1.5% sodium (potassium) carbonate aqueous solution (other alkaline solutions can also be used) to obtain the desired pattern. Finally, the developed coating is cured a second time at 120-160°C for 40-90 minutes to obtain the final cured product. The photosensitive resin composition of the present invention is coated onto a support and dried to form a dry coating film, which is then covered with a protective film. A solder resist dry film consisting of a support, a dry coating film, and a protective film is provided. The thickness of the dry coating film is 10-100 μm. For example, a polyethylene terephthalate film with a thickness of 10-50 μm can be used as a support; for example, a polyethylene or polypropylene film with a thickness of 10-50 μm can be used as a protective film.

[0052] In one embodiment, the amount of the epoxy resin with the specific structure is 10%-60% of the weight of the photosensitive resin composition, preferably 30%-50%. This further improves the dispersibility of the photosensitive resin composition for pigments and fillers, reduces the water absorption of the cured product, and improves resistance to lead-free soldering and wave soldering.

[0053] In one embodiment, the photosensitive resin composition is used for via filling or solder masking of circuit boards. That is, its use in via filling or solder masking of circuit boards. Of course, it should be understood that the uses of the photosensitive resin composition are not limited to those described in this application.

[0054] Compared to existing technologies, the above-mentioned photosensitive resin composition, by introducing a certain proportion of a special-structure monobasic acid α2 into epoxy acrylate, can effectively improve the dispersibility of pigments and fillers in the photosensitive resin composition; reduce the water absorption of the cured product, thereby improving its resistance to lead-free tin spraying and wave soldering. Theoretically, it is speculated that the special-structure monobasic acid has a longer carbon chain and a larger molecular weight, increasing the hydroxyl equivalent of the photosensitive resin composition in the cured product, which can reduce the content of polar hydroxyl groups in the cured product, thus reducing its water absorption; the presence of one or two hydrocarbon groups on the α-carbon of the carboxyl group has a steric hindrance effect on the ester group, further reducing water absorption, and also reducing the attack of flux on the ester bond at high temperatures during lead-free tin spraying and wave soldering processes, making the solder resist layer at through-holes and fine lines less prone to blistering and peeling. Meanwhile, due to the better coating properties of the longer carbon chains on pigments and fillers, they have a better barrier effect. After dispersion, pigments and fillers are less likely to precipitate and agglomerate, which improves the stability of the photosensitive resin composition during storage and makes it less likely to experience floating color or coarsening.

[0055] Secondly, this application provides a solder resist ink comprising the photosensitive resin composition as described in any of the above embodiments. For example, the solder resist ink is obtained by dispersing the photosensitive resin composition as described in any of the above embodiments. For example, to adapt to screen printing or other coating operations, the photosensitive resin composition of the present invention can be diluted to a suitable working viscosity using one or more of solvents such as esters, ketones, ether esters, and aromatics.

[0056] Thirdly, this application also provides a solder resist dry film having a resin layer formed from the photosensitive resin composition described in any of the above embodiments. For example, the resin layer is prepared by coating a film with the photosensitive resin composition described in any of the above embodiments and then drying it.

[0057] Fourthly, this application also provides a solder resist cured product, which is obtained by curing the photosensitive resin composition as described in any of the above embodiments, or by curing the solder resist cured product with the solder resist ink as described in any of the above embodiments.

[0058] The photosensitive resin composition of the present invention can be coated onto a substrate to the desired thickness using known methods such as screen printing, roller coating, electrostatic spraying, or air spraying. It is then pre-baked at 50-90°C for 30-90 minutes to allow the solvent to evaporate, forming a dry coating. A partially transparent film is placed in contact with the coating, and selective exposure with ultraviolet light is performed to form a latent image. Development is performed using a 0.6-1.5% sodium (potassium) carbonate aqueous solution (other alkaline solutions can also be used) to obtain the desired pattern. Finally, the developed coating is cured a second time at 120-160°C for 40-90 minutes to obtain the final cured product. The photosensitive resin composition of the present invention is coated onto a support and dried to form a dry coating film, which is then covered with a protective film. A solder resist dry film consisting of a support, a dry coating film, and a protective film is provided. The thickness of the dry coating film is 10-100 μm. For example, a polyethylene terephthalate film with a thickness of 10-50 μm can be used as a support; for example, a polyethylene or polypropylene film with a thickness of 10-50 μm can be used as a protective film.

[0059] The present invention will be specifically described below through preparation examples, embodiments, and comparative examples, but the present invention is not limited to the embodiments of the present invention. Unless otherwise specified, "parts" or "%" as used below are by weight.

[0060] Preparation Example 1

[0061] 162 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy group molars 1 mol) was added. After complete dissolution, 57.6 g of acrylic acid (0.8 mol), 34.5 g of neodecanoic acid (0.2 mol), 0.45 g of MEHQ (hydroquinone monomethyl ether), and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 54 g of tetramethylbenzene and 92.8 g of tetrahydrophthalic anhydride were added. The reaction was continued for 10 hours to obtain a resin with a solid content of 65% (i.e., an epoxy acrylic resin containing a specific structure). The solid content acid value was 85 mg / g KOH, denoted as A1.

[0062] Preparation Example 2

[0063] 159 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 57.6 g of acrylic acid (0.8 mol), 28.9 g of 2-ethylhexanoic acid (0.2 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 53 g of tetramethylbenzene and 91.3 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as A2.

[0064] Preparation Example 3

[0065] 165 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 50.4 g of acrylic acid (0.7 mol), 51.7 g of neodecanoic acid (0.3 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 55 g of tetramethylbenzene and 95.9 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as A3.

[0066] Preparation Example 4

[0067] 162 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 50.4 g of acrylic acid (0.7 mol), 43.3 g of 2-ethylhexanoic acid (0.3 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 54 g of tetramethylbenzene and 93.5 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as A4.

[0068] Preparation Example 5

[0069] 180 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 28.8 g of acrylic acid (0.4 mol), 103.4 g of neodecanoic acid (0.6 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 60 g of tetramethylbenzene and 103.5 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 84 mg / g, denoted as B1.

[0070] Preparation Example 6

[0071] 165 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 28.8 g of acrylic acid (0.4 mol), 86.5 g of 2-ethylhexanoic acid (0.6 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 55 g of tetramethylbenzene and 100 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as B2.

[0072] Preparation Example 7

[0073] 165 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 50.4 g of acrylic acid (0.7 mol), 51.7 g of decanoic acid (0.3 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 55 g of tetramethylbenzene and 95.9 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as B3.

[0074] Preparation Example 8

[0075] 162 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy molar number 1 mol) was added. After complete dissolution, 50.4 g of acrylic acid (0.7 mol), 43.3 g of octanoic acid (0.3 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 54 g of tetramethylbenzene and 93.5 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as B4.

[0076] Preparation Example 9

[0077] 152 g of diethylene glycol monomethyl ether acetate (DCAC) solvent was added to a 1000 ml four-necked flask. Air was introduced, and the mixture was heated to 90 °C. 215 g of o-cresol-type phenolic epoxy resin NPCN-704 (epoxy equivalent 215, softening point 90 °C) (epoxy group moles 1 mol) was added. After complete dissolution, 72 g of acrylic acid (1 mol), 0.45 g of MEHQ, and 2.1 g of triphenylphosphine were added. The mixture was heated to 100 °C and reacted for 20 hours until the acid value dropped below 3 mg / g. The mixture was then cooled to 90 °C, and 51 g of tetramethylbenzene and 87.5 g of tetrahydrophthalic anhydride were added. The mixture was reacted for 10 hours to obtain a resin with a solid content of 65% and an acid value of 85 mg / g KOH, denoted as B5.

[0078] Preparation of photosensitive resin composition: In each example and comparative example, the materials were mixed according to the ingredients in Table 1 and kneaded using a three-roll mill to obtain the photosensitive resin composition.

[0079] Table 1. Composition ratios of the photosensitive resin compositions in each embodiment and comparative example.

[0080]

[0081]

[0082] The components in Table 1 are as follows:

[0083] Epoxy Resin 1: o-cresol type phenolic epoxy resin NPCN-704, Nan Ya Plastics;

[0084] Epoxy Resin 2: Micronized TGIC, Huangshan Huahui; i.e., micronized melamine triglycidyl ester;

[0085] Acrylic ester monomer: dipentaerythritol hexaacrylate;

[0086] Photoinitiator 1: 2-Methyl-1-[4-(methmercapto)phenyl]-2-morpholino-1-propane, Tianjin Yingli;

[0087] Photoinitiator 2: 2-Isopropyl-Thioxanthone, Tianjin Yingli;

[0088] Filler 1: Fine barium sulfate;

[0089] Filler 2: Micronized talc powder;

[0090] Solvent 1: DBE, Dow Chemical; It should be noted that DBE solvent, also known as divalent ester, dimethyl dicarboxylate, polyol diester, or methyl nylonate (NME), is an environmentally friendly high-boiling-point solvent. DBE solvent is mainly composed of dimethyl succinate, dimethyl glutarate, dimethyl adipate, and mixtures thereof in different proportions.

[0091] Solvent 2: SOLVESSO 150 ExxonMobil; SOLVESSO 150 is an aromatic solvent oil, specifically belonging to high-boiling-point aromatic solvents and paint solvent oils.

[0092] Additive 1: Leveling agent BYK-354;

[0093] Additive 2: Fumed silicon R-972, Evonik Chemicals;

[0094] Additive 3: Defoamer KS-66, Shin-Etsu Chemical.

[0095] Performance evaluation test:

[0096] The photosensitive resin compositions prepared in each example and comparative example were subjected to performance evaluation tests. Samples were prepared and performance evaluation tests were conducted according to the following methods, and the evaluation results are recorded in Table 2.

[0097] Evaluation of pigment and filler dispersibility: Take 300g of the prepared photosensitive resin composition, seal it in a PP material container, add 5% DBE solvent, and observe whether there is any floating color phenomenon on the surface after 30 days.

[0098] ◎: The surface color is uniform, with no floating color.

[0099] ○: A small number of dots of color clustered together;

[0100] X: A clear cluster of colors.

[0101] Preparation of samples for image quality and sensitivity evaluation: The photosensitive resin composition was coated onto a glossy copper substrate using 100-mesh screen printing, with the wet film thickness controlled at 30-34 μm. The samples were then baked in an oven with circulating air at 75°C for 30, 40, 50, 60, and 70 minutes respectively to allow solvent evaporation. Samples used for sensitivity evaluation were baked at 75°C for 40 minutes.

[0102] Sample preparation for hygroscopicity evaluation: The photosensitive resin composition was coated onto a PET film using a wire-bar coater, controlling the wet film thickness to be 30-34 μm. The film was then baked in an oven with circulating air at 75°C for 40 minutes. A 7KW exposure machine was used at 300 mJ / cm². 2 The film is exposed to energy without being placed in the form of film, and then baked at 150°C for 60 minutes. Finally, the PET film is peeled off to obtain a free cured film, which is used as a sample for evaluating hygroscopicity.

[0103] Preparation of tin-resistant samples: The photosensitive resin composition is screen-printed onto a circuit board with copper traces and 0.4-0.5mm vias using a 100-mesh screen, controlling the wet film thickness to 30-34μm. The sample is then baked in an oven with circulating air at 75℃ for 40 minutes. Finally, it is exposed using a 7KW exposure machine at 300mj / cm. 2 The sample was exposed to the light without film and developed with a 1.0% sodium carbonate aqueous solution for 60 seconds. Finally, it was baked at 150°C for 60 minutes. This yielded a sample for evaluating solder spray resistance.

[0104] Volume resistivity test sample preparation: The photosensitive resin composition was screen-printed onto a 20cm×20cm single-sided smooth copper substrate using a 100-mesh screen, controlling the wet film thickness to 30-34μm, while leaving a 2cm margin around the edges. The sample was then baked in an oven with circulating air at 75℃ for 40 minutes. An exposure machine with 7KW and a setting of 300mj / cm² was used. 2 The sample is exposed to energy without film and then baked at 150°C for 60 minutes. This yields a volume resistivity test sample.

[0105] Developerability evaluation: The developability evaluation samples were developed using a developing machine with a developer concentration of 1.0% sodium carbonate, a temperature of 30℃, and a pressure of 2.0 kgf / cm². 2 Rinse with tap water for 60 seconds. Visually inspect the copper surface of the substrate under white light for any residue.

[0106] ◎: Completely clean, with no residue;

[0107] ○: Slight hazy residue remains, acceptable;

[0108] X: Obvious fog-like appearance, unacceptable.

[0109] Sensitivity evaluation: A 21-level exposure ruler was placed on the sensitivity evaluation sample, and the exposure was performed at 200 mJ / cm. 2 300mj / cm 2 400mj / cm 2 Exposure was performed using a 7KW exposure machine, followed by development using a developing machine. The developer concentration was 1.0% sodium carbonate, the temperature was 30℃, and the pressure was 2.0 kgf / cm². 2 Rinse with tap water for 60 seconds. Visually inspect the number of coating cells remaining on the substrate.

[0110] Hygroscopicity evaluation: Weigh the hygroscopic sample using a balance with a minimum reading of 0.1 mg and record it as m1; immerse the weighed sample in deionized water, place it at room temperature for 24 hours, remove it, air dry it at room temperature, and weigh it again and record it as m2; calculate the weight gain rate according to the formula (m2-m1) / m1.

[0111] Evaluation of solder spray resistance: The solder spray resistance samples were divided into two parts. One part was tested immediately after post-curing; the other part was placed in a constant temperature and humidity chamber at 30℃ and 80% RH for 8 hours before evaluation. Evaluation method ①: Apply rosin-based flux to the sample, immerse it in 260℃ molten solder, remove it after 10 seconds, allow it to cool naturally to room temperature, wipe off the flux, and repeat twice. Finally, wash the sample with water and dry it. Evaluation method ②: The steps are the same as evaluation method ①, except that the rosin-based flux is replaced with lead-free solder spray flux, and the molten solder temperature is changed to 288℃. Visually inspect the solder mask layer on the vias and circuits for blistering or coating peeling; if there is no blistering or coating peeling, apply 3M tape to the sample, pull it up at a 90° angle, and visually inspect for coating peeling.

[0112] ◎: No bubbling or coating peeling was observed before and after the tape test;

[0113] ○: No bubbling or coating peeling was observed before the tape test, but bubbling or coating peeling was observed during the tape test.

[0114] X: The tape showed signs of bubbling or coating peeling before testing.

[0115] Volume resistivity test:

[0116] Volume resistivity test before humidification: Before testing, the volume resistivity sample was heated in an oven at 150℃ for 30 minutes and the volume resistivity was tested according to the method of IPC-TM-6402.5.17E; Resistance test after humidification: The sample that had completed the volume resistivity test before humidification was placed in a constant temperature and humidity chamber at 60℃ and 85% for 24 hours. After being taken out, it was placed in a drying oven to cool to room temperature before the volume resistivity test was performed.

[0117] Table 2 Performance test results of each embodiment and comparative example

[0118]

[0119] The unit for volume resistivity in the table is Ω·mm; 5E11 indicates 5 × 10⁻⁶. 11 .

[0120] As can be seen from the test results in Tables 1 and 2, Examples 1, 2, 3, and 4 exhibit balanced and excellent performance in terms of pigment and filler dispersibility, developability, sensitivity, hygroscopicity, solderability, and volume resistivity. In Comparative Examples 1 and 2, the ratio of α,β-unsaturated monobasic acid a1 to monobasic acid a2 with a specific structure in the photosensitive resin exceeds the range of the present invention, resulting in insufficient developability and low sensitivity. In Comparative Examples 3 and 4, the photosensitive resin does not use monobasic acid a2 with a specific structure as described in the present invention, and therefore cannot achieve good results. Furthermore, it can be seen from Examples 1 and 3 that better results are achieved when R1 and R2 in the monobasic acid a2 with a specific structure are both hydrocarbon chains.

[0121] The photosensitive resin composition provided in this application has industrial applicability. As described above, the photosensitive resin and its composition of the present invention can be used as a solder resist material for circuit boards, exhibiting excellent performance in terms of developability, sensitivity, hygroscopicity, solder resistance, and volume resistivity. In particular, it demonstrates excellent performance in terms of hygroscopicity, solder resistance, and volume resistivity, significantly improving the reliability of the solder resist coating on circuit boards. It can be used on carrier circuit boards with high electrical reliability requirements. Furthermore, by using the photosensitive resin and its composition of the present invention, coating a support film can form a dry solder resist film, providing a dry solder resist film composed of a support film, a dry solder resist film, and a protective film.

[0122] Compared to existing technologies, the above-mentioned photosensitive resin composition, by introducing a certain proportion of a special-structure monobasic acid α2 into epoxy acrylate, can effectively improve the dispersibility of pigments and fillers in the photosensitive resin composition; reduce the water absorption of the cured product, thereby improving its resistance to lead-free tin spraying and wave soldering. Theoretically, it is speculated that the special-structure monobasic acid has a longer carbon chain and a larger molecular weight, increasing the hydroxyl equivalent of the photosensitive resin composition in the cured product, which can reduce the content of polar hydroxyl groups in the cured product, thus reducing its water absorption; the presence of one or two hydrocarbon groups on the α-carbon of the carboxyl group has a steric hindrance effect on the ester group, further reducing water absorption, and also reducing the attack of flux on the ester bond at high temperatures during lead-free tin spraying and wave soldering processes, making the solder resist layer at through-holes and fine lines less prone to blistering and peeling. Meanwhile, due to the better coating properties of the longer carbon chains on pigments and fillers, they have a better barrier effect. After dispersion, pigments and fillers are less likely to precipitate and agglomerate, which improves the stability of the photosensitive resin composition during storage and makes it less likely to experience floating color or coarsening.

[0123] The technical features of the embodiments described above can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that the terms "in one embodiment," "for example," and "again," etc., in this application are intended to illustrate the application and not to limit it. The embodiments described above only illustrate several implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A photosensitive resin composition, characterized in that, An epoxy acrylate resin containing a specific structure is formed by adding an α,β-unsaturated monocarboxylic acid a1 and a monocarboxylic acid a2 with a specific structure to an epoxy resin containing two or more epoxy groups in one molecule, followed by adding a diacid anhydride. The monocarboxylic acid a2 with the specific structure is at least one of 2-ethylhexanoic acid and neodecanoic acid. The ratio of the sum of the molar numbers of the α,β-unsaturated monocarboxylic acid a1 and the monocarboxylic acid a2 with the specific structure to the molar number of the epoxy groups ranges from 0.95 to 1.1:1, and the molar ratio of a1 to a2 ranges from 5:5 to 9.5:0.

5.

2. The photosensitive resin composition according to claim 1, characterized in that, α,β-unsaturated monocarboxylic acids a1 include at least one of (meth)acrylic acid, cinnamic acid, and crotonic acid.

3. The photosensitive resin composition according to claim 2, characterized in that, The α,β-unsaturated monocarboxylic acid a1 is (meth)acrylic acid.

4. The photosensitive resin composition according to claim 3, characterized in that, The molar ratio of the sum of the moles of the α,β unsaturated monocarboxylic acid a1 and the monocarboxylic acid a2 with a specific structure to the molar ratio of the epoxy group is in the range of "0.95-1.05":1; the molar ratio of a1 to a2 is in the range of 6:4-9:

1.

5. The photosensitive resin composition according to claim 4, characterized in that, The ratio of the number of moles of a1 to a2 ranges from 7:3 to 9:

1.

6. The photosensitive resin composition according to claim 3, characterized in that, The dicarboxylic anhydride includes one or more of the following: phthalic anhydride, maleic anhydride, methylmaleic anhydride, succinic anhydride, glutaric anhydride, nadic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride.

7. The photosensitive resin composition according to claim 3, characterized in that, The epoxy resin used to prepare the epoxy acrylate resin with the specific structure includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy type epoxy resin, phenolic type epoxy resin, o-cresol type epoxy resin, biphenyl phenolic type epoxy resin, cyclopentadiene type epoxy resin, and naphthol type epoxy resin. The preparation process of the epoxy acrylate resin with the specific structure is as follows: the epoxy resin is added to a solvent, dissolved, and then α,β unsaturated monobasic acid a1 and monobasic acid a2 with the specific structure are added and reacted. Then, a diacid anhydride is added and reacted to prepare the resin. The solvent is at least one of ester, ketone, ether ester, and aromatic hydrocarbon type solvents.

8. The photosensitive resin composition according to claim 7, characterized in that, The solvent is diethylene glycol monomethyl ether acetate.

9. The photosensitive resin composition according to claim 1, characterized in that, The amount of the epoxy acrylate resin with the specific structure used is 10%-60% of the weight of the photosensitive resin composition.

10. The photosensitive resin composition according to claim 9, characterized in that, The amount of the epoxy acrylic resin with the specific structure used is 30%-50% of the weight of the photosensitive resin composition.

11. The photosensitive resin composition according to claim 1, characterized in that, The photosensitive resin composition further includes an epoxy resin containing two or more epoxy groups in one molecule; And / or, the photosensitive resin composition further includes one or more polyacrylate monomers; And / or, the photosensitive resin composition further includes one or more photopolymerization initiators; And / or, the photosensitive resin composition further includes an inorganic filler, the inorganic filler including at least one of calcium carbonate, crystalline silica, fused silica, silicon carbide, alumina, titanium dioxide, zirconium oxide, talc, and barium sulfate; And / or, the photosensitive resin composition further includes an adhesion additive, the adhesion additive including at least one of dicyandiamide, melamine, and imidazole compounds; And / or, the photosensitive resin composition further includes a solvent, which is at least one of esters, ketones, ether esters, and aromatic solvents; the ether ester solvent is diethylene glycol monomethyl ether acetate.

12. The photosensitive resin composition according to claim 11, characterized in that, The photosensitive resin composition comprises the following components: the epoxy acrylate resin with the specific structure, an epoxy resin containing two or more epoxy groups in one molecule, a multi-acrylate monomer, a photopolymerization initiator, dicyandiamide, an inorganic filler, phthalocyanine green, a solvent, and additives, wherein the additives include leveling agents, fumed silica, and defoamers.

13. The photosensitive resin composition according to claim 12, characterized in that, The photosensitive resin composition comprises the following components: epoxy acrylate resin with the specific structure, o-cresol-type phenolic epoxy resin, micronized melamine triglycidyl ester, dipentaerythritol hexaacrylate, 2-methyl-1-[4-(methmercapto)phenyl]-2-morpholino-1-propane, 2-isopropyl-thioxanthone, dicyandiamide, micronized barium sulfate, micronized talc, DBE solvent, SOLVESSO 150, leveling agent BYK-354, fumed silica R-972, and defoamer.

14. The photosensitive resin composition according to claim 13, characterized in that, The photosensitive resin composition comprises the following components in parts by weight: 42 parts of the epoxy acrylate resin with the specific structure, 5 parts of o-cresol-type phenolic epoxy resin, 4 parts of micronized melamine triglycidyl ester, 5 parts of dipentaerythritol hexaacrylate, 3.5 parts of 2-methyl-1-[4-(methimeryl)phenyl]-2-morpholino-1-propane, 0.8 parts of 2-isopropyl-thioxanthone, 0.3 parts of dicyandiamide, 28 parts of micronized barium sulfate, 4 parts of micronized talc, 4 parts of DBE solvent, 1 part of SOLVESSO 150, 0.2 parts of leveling agent BYK-354, 0.9 parts of fumed silica R-972, and 0.8 parts of defoamer KS-66.

15. A solder resist ink, characterized in that, Includes the photosensitive resin composition as described in any one of claims 1 to 14.

16. A solder resist dry film, characterized in that, It has a resin layer formed from the photosensitive resin composition as described in any one of claims 1 to 14.

17. A solder resist cured product, characterized in that, The solder resist cured product is obtained by curing the photosensitive resin composition as described in any one of claims 1 to 14, or the solder resist cured product is obtained by curing the solder resist ink as described in claim 15.

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